(Note: I wrote this a couple days ago, so while Randy’s numbers are still probably the same, since I don’t think he’s had a start in the meantime yet, some of the other stats relating to other pitchers may be a bit off. Still, I think the point stands just fine.)
What is Randy Johnson’s problem this year? His numbers are up (or down, depending on the stat) right across the board. Higher ERA, higher WHIP, higher BB, higher BAA, lower IP, lower SO, etc.
His ERA, however is one of the few numbers dramatically out of line with his career averages. The ERA is more than 1.6 runs higher this year. WHIP is only up .08, and the BAA is up .030 and walks are going to be lower than his career average, though up from the past two years. The real key here is two-fold, I believe. This could well be the first season in 16 years (not counting injury shortened seasons) where Randy has finished under 200 strike-outs for the year. The lower strike-out total means more balls in play and, I suspect though I do not have access to the data, more sacrifices to score runs. I don’t think that is the primary reason, however. I find it hard to imagine that teams are managing to sacrifice enough to score an additional 1.6 runs or so every nine innings.
A bigger reason probably has to do with the patterns and types of hits that Randy allows. There are currently about 23 pitchers who have higher WHIP but lower ERAs, some as much as one or one and a half runs lower. Because there is not a large disparity in home runs, I would speculate that for some reason Randy is giving up more multi-base hits that are not homers, or for some reason he is not spreading out the hits he allows as effectively as other pitchers for some reason.