Miami Marlins starter Josh Johnson did not begin the 2012 season very well. Through the first month, he had an ERA of 5.34. For a pitcher to whom the Marlins committed their first long-term signing in team history, one would expect more. But after one month, Marlins fans had to figure that Johnson would return to normal, even as theconcerns about his velocity have hung around throughout the year with a small uptick in midseason.
But as one might have expected with Johnson's peripherals through the roof to start the season, regression to the mean has gone a long way to returning the ace JJ that we know and love. Johnson's numbers since April's odd schism, his season has been mostly prototypical.
Look at the set of playing time from May until now. A better example of regression to the mean could not be found. Johnson, for some odd reason, was allowing a lot of hits on balls in play in April. He rectified that over the course of the season, putting up a BABIP from May onwards that was extremely close to this season's league average of .293.
So, Johnson has completely returned to normal, no strings attached, right? Well, if you look at the ERA and FIP from the May onwards time period, you can see that it is still a good deal worse than the preseason projection by ZiPS. In our preseason projection, we said that Johnson would be around a 2.99 ERA when we took the average of many different projection systems. He has fallen somewhat short of that goal, but the reason is likely the one we expected all along: velocity.The Velocity Factor
Aside from a slight uptick in velocity in the middle of the season, Josh Johnson has not really regained the speed he had on his fastball from 2009 to 2011. In those seasons, he was averaging around 94.5 mph on his fastball, but this season that number has dropped down all the way to 92.8 mph on average. That is a loss of more than 1.5 mph of velocity on what was once an elite fastball.
So what kind of effect could that have? Friend of Fish Stripes and now performance analyst for the Houston Astros organization Mike Fast wrote a stellar 2010 piece for the Hardball Times that discussed the effect of velocity on run prevention in pitching. Here is the summary:
Being able to bring the heat is a very important factor in a pitcher's success. Being able to crank it up a notch typically improves a pitcher's run prevention abilities, and losing a notch hurts his effectiveness. Starting pitchers improve by about one run allowed per nine innings for every gain of 4 mph, and relief pitchers improve by about one run per nine innings for every gain of 2.5 mph.
The emphasis was mine. The above states that every mile you gain or lose on your fastball is equal to about a quarter of a run up or down in production.
Remember that we expected a 2.99 ERA from Johnson before the season. In his season overall, he has a 3.73 ERA, and his fastball velocity drop of almost 1.5 mph would have expected an ERA of 3.38. The velocity gets us halfway there to explaining the deficit between Johnson's expected and current performance. From May onwards, the velocity went up to 92.9 mph, and that difference yields a similarly expected ERA of around 3.40, which is conveniently right around where Johnson was from May going forward.
In other words, despite that uptick, it seems that Johnson has lost the velocity he once had when he was an elite starting pitcher. But the results we saw were still very good, worthy of one of the better pitchers in baseball, and the loss in velocity, at least beyond the month of April, described almost all of the difference in his expected and true performance. The fact that he allowed struck out fewer batters and walked more hitters during that time period than was expected showed that the drop in velocity also affected his peripherals and that it was not something driven by just BABIP.
Worth An Elite Return?
Before the season began, we thought Johnson was going to be one of the elite pitchers in baseball. But now that we feel certain that Johnson has lost the velocity on his fastball, can he be considered an elite starter? The Marlins certainly thought so, which is why he was being dangled only for a king's ransom at the trade deadline and why the Fish right fully did not trade him in the end.
When we evaluated Johnson at the deadline various times, we assumed him to be around a 4.5 WAR pitcher. But with this velocity, is he that effective? Depending on how many innings he pitches, he can still be that sort of pitcher to the Marlins or to a potential trade partner had a deal come up. If Johnson pitched 170 innings in 2013, he would need to have an ERA of 3.00. If he pitched 180 innings, it would take an ERA of 3.10. For 190 innings, it's a 3.20ERA.
All of those are a little better than the expected talent level we had for Johnson based on his May and beyond performance this year and his dropped velocity. So the Fish may have asked for even more than they deserved in a potential trade. But it does not mean that Johnson is not still a valuable pitcher for the Marlins, especially if he shows he can remain healthy.