The White Sox aren’t close, but they’re building a long-term core. Earlier in the week they signed starting pitcher Jose Quintana to a five-year contract with two more years of club options. Appropriately, given the player, the news didn’t capture the nation’s interest. In fact, the biggest immediate effect was Quintana could stop being such a nervous, uncomfortable wreck. It’s a smaller deal than Starling Marte’s new contract with Pittsburgh, in both guaranteed money and in relevance to the average fan’s interests.

There’s something here, though. Something one wouldn’t expect. Quintana’s 25 years old. Last year, by WAR, he was tied for 24th among major-league starters — neck and neck with the likes of Homer Bailey, Madison Bumgarner and Patrick Corbin. By RA9-WAR, he was tied for 23rd, equal to Jordan Zimmermann and Chris Tillman. He made all of his starts, and he threw 200 innings. A season ago, ever so quietly, Quintana was one of the better starters in the majors. Which leads to this: What the heck is a Jose Quintana?

There is no single tried-and-true metric to measure the underrated player. It’s a feel thing, which means it’s a subjective thing, and players I perceive to be underrated might be different from players who are truly underrated. But not only do I think Quintana is underrated — I think he’s almost a total unknown. Given his background, that’s forgivable. Given his present and probable future, it’s about time to get to know him. Quintana’s story is one to tuck away, as the story of a guy breaking through his own ceiling.

His professional career can be broken down into chapters:

Chapter 1: Quintana signed as a teenager with the Mets. In March 2007, when he was 18, Quintana was suspended for testing positive for a banned substance. At the end of the suspension, Quintana was released, as the Mets had a zero-tolerance policy. It was dumb, to be sure. Quintana was young, to be sure. The following March, Quintana signed with the New York Yankees.

Chapter 2: Quintana was written off by the Yankees. Not immediately, though. He pitched for four years with the organization. His last year, he was an effective swingman in High-A. But when it came to be decision time, the Yankees left Quintana off the 40-man roster, which allowed him to become a minor-league free agent. The Yankees chose to protect David Phelps, D.J. Mitchell, David Adams, Zoilo Almonte and Corban Joseph. This is the reason the Yankees left Quintana off:

GM Brian Cashman said they deliberated on the matter and, despite a dearth of quality lefties in the system, “We looked at him as a fringy prospect. We offered him a minor-league contract to stay, but not a 40-man roster position. We didn’t feel he was ahead of other guys we gave spots to.”

Chapter 3: Quintana made a difference for the White Sox. He was signed in November 2011, along with Donnie Veal. Ken Williams said at the time:

“He’s a strike-thrower,” Williams said. “He can spin the breaking ball. He’s got velocity to both sides of the plate. He can grow up and be a starter. We’re very happy to have both.”

White Sox scouts who’d seen Quintana liked the profile of a steady, strike-throwing lefty — level of competition be damned. Here’s a good article about his discovery and emergence. A few key excerpts:

“Quintana had some nice tools going forward, but the way he went about his job … I thought he had growth and had potential to get better.”

…

“That breaking ball was OK. He could vary the angle, get depth or widen it out to a left-hander. But I thought the changeup would be key. If the changeup gets better, I thought, ‘My gosh. There’s no telling what he could do.'”

…

“I thought he had a chance to be a back-end, a fourth starter. I knew he was a guy who could get some innings. He commanded the ball and could pitch deep into games.”

Quintana began 2012 in Double-A. He wound up hurried to the majors, and in the majors he remained, getting by as the sort of back-end guy he’d earlier been projected to become. In almost 140 innings, Quintana posted average peripherals and prevented an above-average number of runs. He was hardly the exciting type, but he’d arrived ahead of schedule and he made a positive contribution for next to nothing. The White Sox figured they had a half-decent asset.

Chapter 4: Quintana got better. Last season, as a full-time starter, Quintana dropped his ERA- by four points. He dropped his FIP- by six points. He dropped his xFIP- by eight points. The end result was that Quintana finished as one of the more effective starters in baseball. It’s because of that improvement the White Sox decided to commit to Quintana as a part of the core, and that improvement allowed Quintana to become more than he was projected to be even by the scouts who recommended him to the front office.

To really get a sense of things, you have to go to the splits. In both 2012 and 2013, the left-handed Quintana was good against lefties, as one would expect. He reached a new level because he turned himself into a different pitcher against righties. In his first exposure to the bigs, his strikeout-to-walk ratio against righties was 1.5. In his sophomore season, that jumped up to 3.0. A good lefty starter is more than good just a fraction of the time, and Quintana made himself complete.

What happened? Part of it was that Quintana gained about a mile per hour, on average. His fastball got harder, his cutter got harder, his curveball got harder. His changeup… didn’t get much slower. But there was more to the story, and credit has to go to both Quintana and pitching coach Don Cooper, under whom another decent talent has exceeded expectations.

Last spring, Quintana put a lot of work into improving his off-speed pitch. Those minor-league scouts talked about what Quintana could become with a better change. Quote:

“I’m really locked in on my changeup,” said Quintana through translator and White Sox coach Lino Diaz. “I’m working on all areas, but the changeup is the concentration right now for me.”

Against righties, in 2012, Quintana threw 7% changeups. Against righties, in 2013, Quintana threw 13% changeups. In 2012, it wasn’t an actual threat. In 2013, one of every four swings missed, and the pitch didn’t get battered as badly. The in-play results still weren’t spectacular, but Quintana threw his changeup with more confidence and better location, and it stands to reason that improved his whole repertoire.

The story doesn’t stop there. One thing the White Sox liked about Quintana was he wasn’t afraid to come inside. One thing they wanted more of was pitching to the arm side. One writeup:

Then ahead of the 2013 season, pitching coach Don Cooper asked Quintana to work on command to the outside portion of the plate. Pitching inside hasn’t been an issue for Quintana, but hitters stayed away from outside pitches in 2012 knowing he had trouble throwing strikes.

Additionally:

“For me, it’s that he’s able to use all parts of the plate now, not just the one part of the plate. Whenever he got in trouble, it was because he wasn’t able to expand. Now because of his delivery, he’s able to do things pretty easily when you suggest it. He has always been that way.”

In part because of the improved changeup, and in part because of greater mechanical consistency, Quintana opened up the outside against righties, which forced them to cover a bigger area. That’s made the job harder for hitters.

Quintana also had great success with a new two-strike weapon. In 2012, he proceeded to two-strike counts 45% of the time, and he converted those into strikeouts 32% of the time. In 2013, he proceeded to two-strike counts 50% of the time, and he converted those into strikeouts 40% of the time. In 2012, against righties, Quintana picked up 38% of his strikeouts with his four-seamer. Last season that jumped to 65%.

The power fastball became Quintana’s two-strike pitch. Some of those were just well-located on the outside edge, but he also made an effort to blow hitters away up high. Let’s define a high fastball as a fastball around the upper-third of the zone, or higher. Two years ago, in two-strike counts against righties, 29% of Quintana’s fastballs were high. Last year, in two-strike counts against righties, 51% of Quintana’s fastballs were high.

Pitching up also came with another side effect: Quintana tied for the league-lead in pop-up rate. His own pop-up rate more than doubled season to season, and there were improvements there against both righties and lefties. So not only did Jose Quintana push his strikeout rate forward — he also improved in another category of automatic outs, which presumably contributed to his moderately low BABIP.

In Chapter 3, Jose Quintana went from being a minor-league free agent to a decent back-end big-league starting pitcher. In Chapter 4, due to improvements in repertoire and delivery, Quintana went from being a back-end sort to being a legitimate No. 2, behind Chris Sale. I was always blown away by the progress made by Doug Fister. Fister was a non-prospect who has turned himself into one of the better starting pitchers in the game. At the same time, Fister was also a seventh-round draft pick. He wasn’t highly-touted, but he wasn’t nothing. Jose Quintana is probably a step or a half-step below Doug Fister, but Quintana was pulled from the pool of minor-league nobodies, having been left off the Yankees’ roster entirely. Between Fister and Quintana, we don’t have to pick a favorite story. We can be thankful to have them both.

Quintana authored one heck of a fourth chapter in his career. As a result, the White Sox have made a commitment to his fifth. I think it’s fair to say he’s among baseball’s lesser-known starting pitchers. I also think it’s fair to say that will no longer be his fault.