Last season Matt Garza enjoyed a breakout season. His strikeouts increased. His walks decreased. He kept the ball on the ground and therefore in the park a lot more often. He was even so lucky last year that he allowed only 7.7% of his fly balls to leave the yard. While Fangraphs had him with a cool 5.0 WAR, Baseball Reference and Baseball Prospectus weren't so giving. B-Ref's WAR (often called rWAR) was 2.5 while BPro's WARP was 3.7. If you take the average of the 3 it was arguably his best season in his career. ;
This season Garza has seen a small decrease in his strikeout rate (about .7 less per 9) and maintained the same walk rate. He's even managed to hold batters to a BABIP of just .270 and has stranded more runners this year than last. Similar strikeout rate, basically the same walk rate, much lower BABIP, and a lower LOB% and you'd think he'd be just as good. But no. HIs HR/FB% has more than doubled to 16.7%. That's not all though.
His ERA has increased by exactly 1 run. NL average runs per game is slightly higher, but nowhere near as high as a 1 run per 9 increase. Other than the increase in home runs per fly ball, the difference between the two seasons boils down to sequencing.
He's actually been better with bases empty this year (.576 vs. .650 last year), but if you look at the plate appearances and the ones that have the most the difference is considerable. He's been better with the bases loaded, but only 8 times has he faced a bases loaded situation. He's been better with runners on 3rd (less than 2 outs and with 2 out), but only a total of 33 plate appearances. The big difference is the Men on (144 PA), 1st and 3rd (76 PA) and 1st, less than 2 outs (78 PA).
Last year he was a little better than expected in these high leverage situations while this year he's been a lot worse than expected. The end result is an ERA much higher. His wOBA is .398 with men on base. It's over .370 with men in scoring position. Last year both were below .300.
There’s no reason to think he won’t improve, but I do have to admit that I fail to see why people believe Garza is so valuable. He’s a good pitcher, but he’s far from great.