What's he throwing?
First, I should say that statistics involving pitch types are pretty suspect because they are categorized based on the spin and movement of the ball, and each pitcher has different ways of throwing any particular pitch. So blur your eyes a bit, and we'll be just fine. In his Phillies career, Halladay has exhibited a repertoire of mostly fastball-cutter-splitter-curveball-changeup. In his more successful seasons in Philly, he featured fastballs and cutters around 70% of the time, with a sprinkling of curveballs and changeups. In the past two seasons he's diversified, but more importantly lost velocity, throwing fastballs (minus 3 mph) and cutters (minus 3 mph) around 50% of the time, in addition to an increasing amount of splitters (minus 1 mph) and curveballs (same mph). So it does appear that he is recognizing that he doesn't have the velocity he used to, and adjusting by throwing fewer of the pitches that he needs more "oomph" to throw.
How is he dealing with his new "stuff"?
So how has his decline in velocity and increased focus on off-speed pitches affected the way that he has pitched? He's done what you might think he would do -- nibble around the plate. Without a competent fastball or cutter with which to pound the strike zone early in the count, Halladay's first-pitch-strike percentage has dropped by 10 percent from previous seasons. Here's why this is important:
|First Pitch||K%||BB%||Opp. Avg.||SLG|
You don't need me to tell you that starting off with a strike is important, but these early-season numbers from Halladay further illustrate the kind of impact it can have on a game.
Additionally, his increased emphasis on off-speed pitches has apparently caused his pitches that are out of the strike zone to be less enticing, although without a decline in effectiveness. Batters' swing percentage on pitches out of the zone has dropped by 10 percent this season as well, without any difference in swing percentage on pitches in the zone. Bizarrely, this is accompanied by a similar decline in batters' contact rate on pitches out of the zone, without any difference in contact rate within the zone. That means that batters are swinging less frequently at bad pitches, but when they do, they miss more often, keeping the status quo in terms of overall contact and swinging strike rate, but producing odd stat lines (e.g. his peculiar opening outing against the Braves, in which he allowed 5 runs in 3.1 innings with 9 strikeouts).
How has this impacted his in-game outcomes?
Well, negatively. He has shown a dramatic increase in line-drive rate and decrease in ground-ball rate, both of which are correlated with more hits-per-ball-in-play (or BABIP for those more sabermetrically inclined). His strikeouts are down by about 10% from their 2010-11 numbers, while he is walking more than twice as many batters as he was earlier in the decade. The extra baserunners (about 1 more every two innings from '10-'11) may be putting tangible pressure on him, as his strand rate has gone from around 80% for years to around 70% last year and around 60% this year.
All of this brings about pretty much what you'd expect: a lot of runs allowed. Last season, Halladay allowed his highest earned run total since 2007, and that was with 70 fewer innings pitched than the lowest amount he had pitched in any of those seasons. This season, he's on pace to reach that run total in 60 fewer innings than he pitched last season. So, not a great trend.
Where does he go from here?
Maybe his most recent game is a sign that Halladay is starting to learn how to pitch in his new reality. I ascribe absolutely zero probability that he pitches as well as he did between 2008 and 2011 (in which he never had an ERA higher than 2.79), and even most of the seasons prior. But maybe a slightly-above-average season throwing around 200 innings could be possible if he stops nibbling so much, so he can keep his pitch count down and get deeper into games. He should in no way be considered an "ace" anymore, but a passable third starter may something that can be in his wheelhouse. If he posted a solid (and possibly unattainable) 3.50 ERA the rest of the year, he would finish with a slightly-above-average 3.80 ERA for the season. A challenge, to be sure, but I wouldn't put it past a guy with his work ethic.