It isn’t hard to spot the moment that the Calgary Flames’ season took a dramatic turn for the better.

Entering the November 15 road game against the Minnesota Wild, Calgary had lost four straight contests, their fourth multi-game losing streak of the young season. The Flames were just 16 games into the schedule, but were already six games under .500 and five points out of the playoffs; no team in the league was on pace for a worse finish.

The Flames beat the Wild, but lost Johnny Gaudreau to an Eric Staal slash in the process. That story dominated the post-game discussion, but it wasn’t the most significant event that night. The most significant event was Chad Johnson’s 27-save shutout, the first of the season for Calgary, and a welcome change of pace after a four-game run of allowing four or more goals.

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It was the moment Johnson succeeded Brian Elliott as the team’s starting goaltender.

Johnson had always been a fallback option in the event that Elliott struggled. Calgary signed him after a 45-game run with the Sabres in 2015-16, one in which injuries had thrust him into the No. 1 position and he had responded with a .920 save percentage performance. In a summer free agent market where backup goalies were a dime a dozen, the Flames invested $1.7 million—twice the going rate of some other ‘tenders—to be certain they had some depth in net.

With Johnson in net, Calgary would go on a run and re-establish itself as a competitive franchise. After winning just five of their first 16 games, the Flames would lose only five of their next 16, pulling themselves back up to 0.500. Three key things changed between the first and the second run, and Johnson was the primary driver of two of them:

At even-strength, both the successful and unsuccessful versions of the Flames scored 26 goals over 16 games. The entire improvement there came in the goals-against department, which was slashed by more than one-third, from 33 goals all the way down to 21. That was nearly a full goal-per-game improvement all by itself.

Not all the credit for that should go to Johnson. Calgary’s shots against rate was basically flat, but the Flames have done a better job in the defensive zone of late, reducing the average number of scoring chances against by about 20 per cent. Nevertheless, that only explains about half the improvement in the team’s save percentage, which ballooned from a miserable .901 at 5-on-5 all the way up to .943.

The latter number is probably too good to last. Johnson’s career 5-on-5 save percentage is in the .925 range, which is the league average these days. He’s as hot now as Elliott was cold to start the year, and the end result is that over 32 games the Flames are right about even at 5-on-5. That’s probably where they should be; for all the peaks and valleys the shot and scoring chance metrics suggest a pretty average team.

The penalty kill is the other area that has been saved by the switch in goaltending. The Flames had a nine-goal improvement between their first 16 games and their most recent 16, and it’s pretty much entirely driven by save percentage. Calgary is actually allowing more chances against/hour than they were earlier in the year, but nevertheless the save percentage has climbed from a wretched .803 up to a glorious .918.

The league average is about halfway between those extremes, and again it’s reasonable to conclude that the Flames should be about average in this department based on Johnson’s history. It’s a better idea to trust the average result of that early lull and recent peak than it is to put too much faith in either result on its own.

The one improvement not being driven by goaltending is on the power play.

The Flames don’t appear to be special on the man advantage, but they aren’t awful either. They’re just a touch below average at generating shots, and the problem early in the year was that too few of those shots were scoring chances. Over the first 16 games, one shot in three that Calgary took was a chance; over the past 16 that number has climbed to 50 per cent.

To some extent, this seems to be a result of a shift to more frequent down-low plays. Over the first 16 games, Calgary defencemen took more than half of the team’s power play shots—and almost none of those shots were chances. Over the past 16 games, Flames forwards have shot more frequently, and more of the power play shots have been legitimate opportunities to score.

There’s been some luck involved—as Mikael Backlund can attest—but for the most part the Flames are scoring thanks to strong work down low. Troy Brouwer and Sean Monahan have been particularly effective in this regard lately, having combined for four goals in a span of 10 days off down-low plays.

That power play spike wouldn’t matter if it weren’t for the goaltending, though. For the second year in a row Johnson has been pushed into a starting job by circumstance, and for the second year in a row he’s deserved high praise for his work. His recent run has saved Calgary’s season, and as long as he can put in average work the rest of the way the Flames should be OK.

That he’s on the roster at all is of course a testament to Calgary’s management. It would have been easy to bring Elliott in, proclaim the position fixed and call it a day. Instead the Flames brought in a backup who could push and if need be replace Elliott. Had they picked a lesser option they wouldn’t be in the thick of the playoff race today.