There are stats that show a correlation from year to year and stats that do not, the ones that do not I tend to think of as luck. BABIP, HR/FB, LOB% vary a lot from year to year for most pitchers. When one of those stats its way outside its career value I think of it as most likely luck. When a stat like K/9, BB/9, GB% is outside its norm I think something has changed with the pitcher because those stats are generally pretty steady year to year. Dave Bush has 6.26 K/9 for his career, 6.64/9 this year. 1.85 BB/9 for his career, 1.79 BB/9 this year. 45.2% GB for his career, 44.9% GB for this year. All of his stats that tend to correlate from year to year are at or better than his career numbers. BABIP is .331 compared to a .294 career line, LOB% is 61.1% compared to a 67.6% career line (this is low which indicates he does have a long term problem with it). 10.5% HR/FB vs 11.1% career line. If you adjust these stats to career norms his WHIP and ERA look a lot like his career values. Basically Bush has given up a lot more hits than you'd expect because of his BABIP and he's let in a few more than you'd expect even for him. To me it just screams luck, pitchers that have stats like this almost always regress towards their career norms. If even one of his peripheral stats was off base I could see it being a mechanical issue etc but the only thing out of whack is a stat that pitchers seem to not have a lot of control over. He is missing as many bats as normal, he's hitting the strike zone as much as normal, he's not giving up more flyballs than normal, just more balls are finding holes this season. Using a scouting based approach I've seen with my own eyes that he's given up a ton of little bloop hits, misplayed balls that didn't go as errors, etc and I think they easily explain most of the struggles. Hall doesn't muff the double opening day and Bush gives up 3-4 fewer ER's, Bard gets his check swing called a strike and he gives up 4 fewer in SD, the bullpen stops a couple runs in the two early season games he was pulled with 2-3 runners on instead of letting them all in its a little better. The texas game saw two bloop singles, a bunt for a hit force him out etc. These things happen to every pitcher but it seems to be an epidemic in Bush's games this season and I highly doubt it keeps up.