On the morning of a mid-March game against the Calgary Flames, the St. Louis Blues goaltending coach, Jim Corsi, was minding his own business when a shot rang off the crossbar and clunked him on the forehead.

Momentarily stunned, and bleeding, Corsi skated off the ice and was greeted in the corridor outside the dressing room by Martin Brodeur.

Brodeur is a member of the goaltending fraternity, recently retired, and now working for the Blues as a special assistant. Brodeur demanded to see the damage – a lump the size of a golf ball had formed, and a bluish bruise was in the process of forming. Naturally, the two started to compare war stories because, after all, that's what goaltenders do.

Story continues below advertisement

But in a world where most people know Corsi only as an advanced statistic, here was living proof that there was an actual flesh-and-blood human being behind the equation.

Corsi, the formula, measures the shot-attempt differential of a player while on the ice, helping to usher in a new era of analytics that is sweeping and dividing the NHL community.

Corsi, the person, is in his first season as the Blues goaltender coach, after spending the previous 16 years doing for the same job for the Buffalo Sabres. In his time with Buffalo, Corsi worked with Dominik Hasek and helped Ryan Miller develop into an NHL star.

He is also an engineering grad, a former school teacher and a teammate of Wayne Gretzky's during the Edmonton Oilers' inaugural NHL season, responsible for eight of their 28 regular-season wins that year. Corsi played more than a decade professionally in Italy.

During his early minor-pro days, spent time in the old North American Hockey League, he played with and against many of the characters who inspired the movie Slap Shot. He was also one of the NHL's first full-time goaltending coaches, grew up in Montreal, attended Concordia when it was still Loyola University, briefly played professional soccer for the Olympique, and is now coaching the Blues' goaltending tandem of Brian Elliott and Jake Allen.

In short, with Jim Corsi, there's a lot to get to know.

And yet, for the vast majority of casual hockey fans, Corsi is synonymous with a measure, not a man.

Story continues below advertisement

"It has taken on a life of its own," Corsi acknowledged. "I remember telling my wife, 'I'm not Fahrenheit.' When people talk about it, they don't say it's the statistic named after Jim Corsi. They say, 'He has a Corsi of … .'

"I had become an inanimate object. I had become Kleenex."

The story of how Corsi, now 60, came to be part of the analytics movement begins in the mid-1970s, after he'd graduated from Loyola with an engineering degree and was pondering several career choices. The Kansas City Scouts had him on their college protected list, but by the time Corsi was ready to consider pro hockey as an option, they'd moved to Colorado and become the Rockies.

Ultimately, a conversation with Ken Dryden, then a star goalie with the Montreal Canadiens, persuaded him to give pro hockey a try instead of venturing out in the working world as an engineer.

"It's remarkable because both Ken and Dave Dryden had major impacts on the arc of my career," Corsi said. "My wife and I were college-educated and we had a pretty good future going if we'd stayed with that. At the time, NHL contracts weren't that big. We weren't going to get rich. Ken said, 'Jim, give it three years. You can always be an engineer in three years, but you can't come back to hockey in three years – and if you don't try it now, you'll never know what you could have been.' I thought that was great advice – and after three years, I was in the NHL.

"Then it was Dave Dryden retiring that got me into the NHL with Edmonton. He was really good for me because he was the first to talk about goalie coaching. He had an analytical mind. He'd say, 'More goals are coming in from here than there, so maybe you should work more on these skills.' And I'd think, 'Yeah, that makes a lot of sense.'"

Story continues below advertisement

It was the first hint Corsi would have a future, instructing goalies, and it began when he began tweaking his own game and technique.

A second career crossroads came soon after his rookie NHL season with the Oilers. Unhappy about being bounced from Edmonton to Oklahoma City to Houston in the 1979-80 season, and cognizant that he'd given pro hockey the three years he promised, Corsi decided he might have a brighter future doing something else – until he got a call from Dave Chambers, then Italy's national team coach.

Chambers telephoned Corsi at his mother's Montreal home to offer him a chance to play in Italy and she hung up the phone (Corsi tells this story, mimicking a heavy Italian accent).

Ultimately, Corsi reached Chambers, decided to try Italy for one year and stayed for 12, playing mostly for AS Varese. In all, he made eight appearances for Italy at the world championships and in 1982, was in goal when Italy shocked a Canadian team that included Gretzky by tying it 3-3. In that same tournament, it also defeated the United States, pushing it into the B pool for the following year's worlds, a result that would cause him a moment's grief during a job interview some 15 years later.

When Corsi retired after the 1991-92 season, he moved back to North America and started teaching part-time, consulting with teams part-time and doing some colour work alongside Dick Irvin on Montreal Canadiens broadcasts.

In the meantime, he sent applications through the mail, seeking a job in the NHL as a goalie coach. That first year, he got an interview with New Jersey Devils general manager Lou Lamoriello, made the short list, but didn't get the job. For five years, he kept trying and not getting anywhere. In the summer of 1998, just at a point when he was exploring doing a PhD in education sciences, the Sabres called and asked him to interview. It was a turning point.

Story continues below advertisement

"I had listed Mark Napier as a reference because I'd played with him in Europe and [Sabres' coach] Lindy Ruff had called Mark to ask about me," Corsi said. "So I'm in the room with Lindy Ruff, Don Luce, Terry Martin, all the big wigs with the team and [GM] Darcy Regier walks in and says, 'I don't know anything about you, but our assistant coach, Mike Ramsey says you're the bugger that forced the USA to go down into the B pool at the world championships' because we'd beaten them and it forced them to go down.

"I'm sitting there, I took my glasses off, I say, 'Well, I guess this interview is over.' And they all started to laugh. So I think, 'Maybe it's not over.'

It wasn't. Corsi returned to Montreal, where he'd been offered a full-time tenured position teaching high school math and science. Then Buffalo called and offered him the job – part-time to start. After talking it over with his wife, he took it.

"Without the strength of my wife, and the ability to say, 'well, let's try it,' it wouldn't have happened,'" Corsi said. "Here I am."

Regier, laughing all the way, confirmed the story of that first interview and says that in all the years they subsequently worked together, he found Corsi to "be a very interesting guy because of his high level of curiosity.

"He's one of those life-long learning people and it's not focused in one area. It's all over the map. There are a lot of things that interest him. He's high energy – and does the best Groucho Marx impression of anybody I know. In that regard, he's very youthful, a very good person."

Story continues below advertisement

Ruff, now coach of the Dallas Stars, had a clear affection for Corsi, describing him as "a very articulate, intelligent man. He's 100-per-cent loyal, just a really good guy, who loves to talk. I would say to him, 'Jimmy, don't ask me a question you know the answer to already.' If you were sharing stats, he would come up with formulas, different from the NHL's, that you could use and would help you."

Corsi was at the forefront of the NHL's trend toward hiring goalie coaches. Previously, teams tended to use goalie consultants, who weren't officially members of the coaching staff. Instead, they'd parachute in a handful of times a year, or if a goalie was going through a slump, to work on technique and sometimes, just to talk about the job, which was so distinct from what a position player might go through when he struggled.

"In those days, if the goalie wasn't stopping enough pucks, the solution was just to get another goalie – not to work with the goalie to make him better," Corsi said.

"For me, the real change came after the 2004-05 lockout. More and more teams started to hire full-time goalie coaches. They were no longer consultants – and there was new pressure on them to make sure the kids in the organization were developing. It wasn't enough just to mentor goalies. There was a teaching role. Development was required. You'd be back and forth between the NHL team and the minors. Now, they even have full-time goalie coaches in the minors.

"So it's evolved – to the point, where goalie coaches' heads are now rolling. They used to be untouchable. If the goalie coach got the job, he was there for keeps. Now, it's to the point even this year, two teams [Edmonton and Philadelphia] released their guys in mid-season. That sends tremors. It used to be a safe haven. Now, he's just a coach involved in developing players."

In Buffalo, Corsi had a chance to work with Hasek, coming off two consecutive Hart trophy wins, and eventually Miller, drafted 138th overall in 1999, the year after Corsi joined the organization. In Buffalo, Corsi developed a formula he said was designed to measure a goalie's workload.

Story continues below advertisement

Based on his own playing experience, Corsi theorized that simply counting shots on goal was not an accurate barometer of how much work a goalie did on any given night. Instead, he believed a goaltender could exert just as much effort or more trying to stop a shot that never made it through to the net, as he did an actual recorded shot on goal.

As a result, he incorporated blocked and missed shots into his analysis of a goalie's workload, on the grounds that goaltenders still had to be prepared to move laterally across a crease on an odd-man rush, or lunge for a shot that might be just high and wide of the net. These goalie "actions" were as physically taxing as recorded shots on goal. Moreover, he also placed a greater value on tracking viable scoring chances, as opposed to simply shots, some of which, taken from far range or a bad angle, were often relatively harmless.

The method behind the madness was simply to help his goaltending charges train more efficiently.

Corsi's groundbreaking work eventually landed in the hands of several Internet bloggers who refined them many times over, by adding new variables.

"Literally, from the time he started until the time he left, he was a math teacher, so he was always deep into numbers," Regier said. "You'd have these conversations with him: 'What do you think of this? What do you think of that? We used to joke about it because Lindy [Ruff] or someone else on the staff would joke, 'Jimmy, you're just trying to find another way to make the goaltenders look good.' He would talk to whoever would listen about not just save percentage, but scoring-chance save percentage. I don't know when the analytics people got ahold of it, but Jimmy was doing that a long time ago, and for as long as I can remember."

But Corsi also believed his role was to work with a goalie's strengths as well as trying to correct his shortcomings.

Hasek, for example, played an unorthodox style. In someone else's hands, he might have been asked to completely remake his game. Corsi didn't. Corsi wouldn't. Speaking at the Hall of Fame last November following his induction, Hasek said his career in North America was largely aided by goalie coaches who didn't try to reinvent his game into the cookie-cutter style of the era.

"What is it that makes Dominik so good?" Corsi said. "He thinks like a player but plays like a goalie. That, for me, was the essential thing. I played goal as a player, but I was a forward in soccer and it influenced my philosophy. The successful goalies today, they think like forwards and play like goalies. Look at Dominik or Marty Brodeur, bookends for my career right now. Two entirely different skill sets and styles, but both very successful. If you look at all the successful goalies, they could see what the play was going to be. People would say, 'Was he ever lucky to be in that spot.' No, he was waiting for it. He could see what was going to happen.

"My biggest and constant challenge to goalies is telling them, their biggest strength is playing hockey. If you want to stop pucks and just stop pucks, you're doomed."

Last year, after the Sabres' housecleaning, Corsi was without an NHL position and working with the national team in Italy when Blues GM Doug Armstrong called and asked him to interview for the opening in St. Louis, a job he ultimately landed. St. Louis is in contention for the President's Trophy as the NHL's top team and its goaltending, which has been excellent this season, will be under scrutiny as the Blues try to win their first Stanley Cup in franchise history.

In St. Louis, Corsi says he's "working with an exceptional staff and a great group of kids. Elliott, Allen, [Jordan] Binnington, the young kid, all of them are really responsive to the stuff I'm doing. It may not be the same as what they're used to seeing, but their response to the workload has been really good. Part of it is trying to keep the drills fresh and applicable.

"When I went back to school to learn about teaching, one of the things I learned was about the psychology of how people learn. In teaching, the research shows one of the worst retention levels is through lecture. So as a coach, the best way to teach a goalie to do a drill is to show him how – by doing it yourself. I remember being in youth hockey and the coach would start screaming if you didn't do the drill properly. I'd think, 'They're not deaf, that's not the problem.' With the pros, if the drill goes sour after I showed them, I'd say, 'Stop, stop, stop,' and say, 'Guys, my fault, I didn't explain it properly.' People learn visually, audibly, tactilely. Some guys, when they hear a drill explained, they go to the back of the line, because they want to see how it's done."

The value of analytics has divided the hockey community into two camps. Corsi believes it doesn't need to be so. Instead of being framed as an either/or proposition, the reality is, you can be in both. They are a measure of past performance and can provide a clue to future behaviour.

But they are not to be taken as absolutes.

"I think where it's going to go is to a place where people can say, 'I'm going to have an opinion, you're going to have an opinion, but ultimately, it is only part of a picture that allows us to interpret what went on in that game,'" Corsi said. "To hang your hat on it in too clinical a way is dangerous, because lots of stuff goes on in a game. I hope there's not paralysis by analysis, because our game is too fast. It's not football. It's instinctive. But some of the analysis will tell you if a guy has some issues, so maybe you don't want him on the ice in the last minute or two.

"As a coach, I often say, if you think with your heart, you end up with heart disease. You have to be really careful with that. But ultimately, you get patterns. You start seeing things [in the analytics] that match what you're thinking. It's something that allows us to interpret the qualities of what that athlete is doing, but it is not Fahrenheit. The temperature outside today is an absolute measure, a fact. Analytics are not an absolute, but they are numbers that help the debate move forward.

"I used to get hate mail from people who'd say, 'I'm old school and what do you know?' What do I know? It's just like plus-minus. You have to take it with a grain of salt. For me, I just look at my body of work. Dominik Hasek asks me to be one of his guests at the Hall of Fame. Marty Brodeur, who doesn't know me from Page 9, comes in and invites me to talk video with him because he wants to make sure his game is right. Those are the things that matter for me. The fact that I'm still employed in hockey is more than enough."

As for the fact that his name is now associated with a hockey statistic in the same way that a 17th-century German physicist, engineer and glass blower is associated with a temperature scale, Corsi is okay with Corsi.

"Even my kids, their friends would say to them, 'the Corsi number, it's cool you have the same name as them.' They'll say, 'Well, no, it's my dad.'

"But it's wonderful. It's humbling. It's quite a funny story how it got that name, but I'm okay with that. I don't feel marginalized. I'm actually quite pleased in the grand scheme of things. It's nice to hear the debate on analytics has been expanded. My only concern is it's almost gone too far the other way – what is reality, other than what the numbers show? – because there's more to it than that.

"I often say, 'Statistics are like a lamppost for a drunkard. You can either use it to lean on or to illuminate.'"