After taking down the Yankees yesterday afternoon, J.A. Happ is now 22-5 with a 2.70 ERA in 213.2 innings since being traded from Seattle to Pittsburgh on July 31, 2015. Other metrics don't like his results quite as much (3.38 FIP and 3.67 xFIP), but by any measure he's been a well above average starting pitcher after a career of mostly mediocrity as a backend type.

There's been a lot of attention paid to how and why this happened. Happ threw his (four seam) fastball more after the trade. His release point was more consistent, and he was getting a little more movement. A lot of this was attributed to Pirates pitching coach/guru Ray Searage, who apparently noticed some issues in his delivery and had him raise his arm slot to be more direct to the plate. Most of this was from last fall/winter, before the Jays signed him and his 2016 season.

But for all those supposed changes, what's really more remarkable to me is how much the new Happ was and is the same as the old Happ. Usually, when a pitcher breaks out or reinvents himself, there's some really obvious tangible physical difference: a new pitch, more velocity, a lot more movement, etc. Rich Hill came out of nowhere at roughly the same time as Happ, but with a highly effective curveball. Marcus Stroman famously picked up a two seamer. Drew Hutchison slowed down his slider and got better break on it (for a while anyway).

In terms of results, Happ's time since then can be divided into three segments (ERA/FIP/xFIP):

Post-deadline 2015: 63.1 innings, 1.85/2.19/2.90 First half 2016 (April to June): 99.2 innings, 3.70/4.48/4.58 July/Aug 2016: 50.2 innings, 1.78/2.73/2.83

After dominating in Pittsburgh, Happ posted a solid ERA but advanced metrics that looked a lot more like the old Happ all told for the first three months of the year. But since the beginning of July, he's once again been dominating. To some extent, these are arbitrary endpoints, but can we can use them to isolate something he's done differently in those dominant stretches to identify or confirm the source of his success?

It's not velocity, which has been quite consistent. He has upped his use of hard pitches a little recently, as he did at the end of 2015. He's also moved away from his two seamer, which he was using more than ever for the first three months. In terms of movement, I don't see any significant changes over time either horizontally or vertically, especially when it comes to changes that fit the pattern of when he's good and bad. In terms of release points, his horizontal release point has moved around a lot over time, but I don't see any changes that fit a pattern fo when he's good and bad. It does appear there's increased intraseason consistency. Vertically, the last couple years look pretty consistent.

In his first stint with the Jays, Happ was the pitcher who frustrated and confounded me the most of any with significant innings on the roster. A lefty with a fastball averaging 92-93 MPH and the ability to dial up 95 with serviceable secondary pitches should be the foundation for a pretty good starting pitcher, but year after year Happ floundered in mediocrity. He flashed the potential for more, once in a while completely dominating an opposing line-up with seeming ease.

But way too often, instead of Dr. Jekyll, we got his alter ego Mr. Happ, who nibbled around the edges, worked deep counts, issued too many free passes and had to deal with lots of runners. If he limited the damage, he still often up near 100 pitches in the 5th inning; otherwise it was a recipe for a lot of runs. But such is the nature of baseball, and when the Jays moved him at the end of 2014 after his age 32 season, it looked like he was what he was, a decent backend starter.

And then the renaissance.

So what happened? It looks to me like it's really about fastball use, and particularly four seam fastball use. He's aggressively challenging batters, and he's got good enough stuff to make the approach work well. In any event a lot better than before.

And to buck the conventional wisdom some, far be it from me to question the genius of Searage, but I'm not convinced he had much to do it with Happ. Maybe he suggested the fastball heavy approach, or maybe some of those mechanical tweaks he suggested were critical in enabling the fastball-heavy approach to succeed. But it's certainly not obvious in the data. And unlike the night and day difference in Aaron Sanchez command-wise in 2016 compared to previous, it's not obvious - to me at least - that Happ's command is much different now than before.

Instead, I think there might be a much simpler answer, Occam's Razor in essence. After bombing out in Seattle as a 33-year-old impending free agent, Happ just let it fly - what did he really have to lose at that point. If he was going to put up mediocre results, you may as well get beat with the good ole #1. He's using the tools he already had, just much more effectively.

Yesterday was a good example of that. After the Jays staked him to the 3-0 lead, he came out and gave up a first pitch leadoff home run to Gary Sanchez on a poorly located 90 mile an hour fastball. Not a great outcome, certainly, but far from the end of the world with none on, and he still had a two run lead. And then he struck out the side on 13 pitches, nine of them fastballs. He went on to give up two more home runs, as he went after the Yankees aggressively. But both were solo home runs, and he piled up strikeouts and limited the free passes that in past years have plagued him.

And that more than anything, is the difference between the new and old J.A. Happ.