They really stick with a bad pitcher because he was successful the year before. That is about the only way to explain why Bannister and his 5.96 ERA are still in the rotation. We seen this in 2005 with Lima (6.99) & Greinke (5.80) and in 2004 with May (5.61) & Anderson (5.64). They all were pretty good one year and ineffective the next. Much like Bannister, in his last 20 starts dating back to April 30th he has a 7.02 ERA. Wasn't he supposed to be a better pitcher when his K rate went up? It was 4.2/9 last year and is 5.8/9 this season. That is impressive improvement but he is getting knocked around and over the yard.
Some called him lucky last season and unlucky this year. I think there's probably more to it than that and I wonder if the adjustments he made to try and up his K rate have ended up negatively effecting his performance. No way to know that for sure I suppose but in his best three starts this season he has 12 K's in 24 innings (4.5/9) so it would seem he is at his best when pitching to contact - or maybe he was just lucky those three starts.