You forget that ERA+ factors in relievers, not just starters, and in this day of bullpen specialization a 3.75 ERA from a reliever is mediocre. While starters account for ~60% of innings pitched (5.8 IP/start last season), relievers account for ~40% of innings pitched. I'm not sure how to calculate it just for starters, but an ERA+ of 105 for a starter is better than for a reliever. No matter how you cut it, it is above average. Also, it has been calculated (this was a year or two ago) that one WAR is on average worth ~$7-9M in salary league-wide. His 2.0 and 2.7 WAR seasons would have been worth approximately $16M and $21.6M in salary from an equivalent player, making him and his salary those seasons a bargain. I'd strongly argue that is not "mediocre" performance. The 1.0 WAR in 2012 was due to making only 18 starts; extrapolate it to 32 starts and you have a WAR of ~1.8, worth about $14.4M in salary. Based on that, yes, I'd say that plenty of GMs wold take a chance that he would recover to career norms because prior to last season his salary was a bargain. Regarding park factors, and if you want to limit the analysis to performance since 27 (we'll say since he left TB), Globe Life Park in Arlington is rated as the 15th most hitter-friendly park, Wrigley Field the 10th most hitter-friendly, and Miller Park the 2nd most hitter-friendly. He hasn't had the benefit of having half of his starts in Petco, Citi, or Dodger Stadium.