The short version of the old book on James Shields that he was a flyball and strikeout guy with a home run problem. That version of James Shields might care about leaving a home park that suppresses home runs. Except that version of James Shields doesn’t exist any more and his new home park is even friendlier.
It’s true that Shields used to give up home runs — his home runs per nine rate was higher than the league average every year but one going into 2010. A little tinkering with his pitching mix — maybe more of that cutter over recent years — and a little velocity (92.3 mph in 2012, 90.9 career), and his ground-ball rate lurched forward. Two of his three best ground-ball seasons have come over the last two seasons, and so have his two best home run rates.
It’s also true that the Rays’ home park suppresses home runs (by three percent) and that Shields had a nice home ERA (3.33) when compared to his road number (4.54). But those two things aren’t linked — Shields had a better ERA at home because he pitched better at home, and it wasn’t the park that aided him. Shields at home had better strikeout (22.1% to 19.2%), walk (5.4 to 5.9%) and ground-ball rates (45.2% to 45%), so it’s not surprising his FIP (3.37 to 4.38) followed suit. But he also allowed 9.9% of fly balls to leave the park at home over his first seven seasons, and that’s basically league average. Hard to give his home park a huge assist there.
What’s more likely the problem was that Shields was pitching in tough parks on the road. His road HR/FB was well above league average (13.9%), and that was over 674.2 innings spent in the same division. The Yankees (111 home run park factor), Orioles (109), and Blue Jays (105) are all in the top five coziest parks for home runs in the league. His new division has the White Sox (112 HR PF, worst in the league), but also the Twins (92), Indians (96), and Tigers (102) playing friendlier to Shields.
It’s tough to predict offenses for a whole division, but the added games against those teams should reduce the competition level some for Shields, too. Last year, the Orioles, Blue Jays, Yankees and Red Sox scored 2,966 runs. The Tigers, White Sox, Indians, Twins scored 2,842 runs. The weighted runs created tell the same story, too. It looks like the lineups he’ll face will play friendlier, too.
In the end, moving to a home park that suppresses home runs 5% more than your old home park can’t be a bad thing. And moving out of the division will be obviously be helpful. Few pitchers actually add velocity — Rick Porcello and Max Scherzer were the only other two starters (with more than 150 innings pitched in the last two seasons) that did so in the last two years, and they’re younger — so saying definitively that he’ll keep that gas seems folly, but he was pretty good in 2011 without all that gas, too. Most of these things seem to bode well for the pitcher going forward, so that the old story and those old home runs don’t come back.
It’s the ground-ball rate that should reduce the opportunities for the hitter to go yard, as much as any of this, so it’s the ground-ball rate that might be the number to watch in the early season. Even in new digs.