The all-time record for wild pitches stands at 30 by Red Ames of the New York Giants back in 1905. A.J. Burnett currently leads the majors with 20 wild pitches.
Why is this significant? Because pitchers back then threw a lot more innings than they do today so percentage-wise Burnett is one of the wildest pitchers in history.
Jacob Peterson of Beyond the Boxscore took a look at Burnett’s 2011 season and determined that even though there have been pitchers who have thrown more wild pitches, Burnett, who is wild with 6.3 percent of his total pitches, is the wildest pitcher who has qualified for the ERA-title since 1950.
Even going back to before 1950, he still has to be one of the wildest ever. Consider that Burnett has thrown just 166.1 innings compared to Ames’ 262.2 innings. He is currently ranked 18th for the all-time single season wild pitch record, but with a few more starts on the way he could break into the top 10 with just three more wild pitches, regardless of innings thrown.
This stat is probably the biggest reason for his discrepancy between his 5.25 ERA and his 4.04 xFIP. Burnett is not just unlucky, he can’t find the plate and constantly is giving runners extra bases all by himself. Hard to pitch when you are doing that.