Thursday, October 8, 2015
Scouting the Offseason: Should the Giants Sign Jordan Zimmermann?
The Giants offseason plans are well known. They need to upgrade their starting pitching if they intend to compete for their 4'th consecutive even year championship. The only questions left are what SP's they are going to acquire and how much are they willing to pay. One available free agent pitcher seems like a perfect fit. That would be Jordan Zimmermann of the Washington Nationals. While he is not a top tier starter in the same class as David Price and Zack Greinke, he is solidly in the second tier and that makes his price tag potentially more palatable to Giants management.
There is one factor in Jordan Zimmermann's resume that should make the Giants think twice about giving him a large, long term contract, which is likely what it would take to sign him. He had Tommy John surgery in 2009. You might respond to that concern by saying all pitchers are at risk of injury at all times. Zimmermann has already successfully recovered from his surgery. There are many very good pitchers in the major leagues who have undergone the procedure. I will counter with some data about Tommy John surgery I have gleaned from articles in Hardball Times, Baseball Prospectus, ESPN and Viva El Birdos. If you want to look them up for yourself, you can use the search words Tommy John Surgery Recurrence.
1. The number of pitchers undergoing Tommy John surgery is increasing over time. At the same time, the number of repeat Tommy John surgeries is increasing at an even faster rate.
2. Long term data from TJ surgeries done between 1974 and 1999 are now complete. Data from 2000-2009 in nearly complete. 20% of MLB pitchers who undergo TJ surgery never pitch in the major leagues again. The median career survival after TJ surgery is 100 innings pitched. 95% of pitchers who undergo TJ surgery with a mean age of 22 years are retired within 10 years.
3. The demographics of pitchers who need TJ surgery is changing with a strong trend toward younger, harder throwing pitchers. Jordan Zimmermann was one of the first of the younger type of pitcher to undergo the procedure. You might even call him the index case of the new TJ epidemic.
4. The career survival curves for pitchers who underwent the procedure between 2000-2009 is significantly lower than for those who had it 1974-1999. It is too early to know how the career survival curve for surgeries done from 2010 on will compare, but lower end of the projected range is farther from the preceding curves than the top end.
5. I was not able to find full career survival curves for second TJ surgeries, but 35% of pitchers who have a second procedure never pitch another MLB game and the performance levels of those that do are generally quite poor.
Of course, there are always exceptions such as Tommy John himself and AJ Burnett who has had a long post-TJ career and is a hard thrower. In general though. We also do not have comparison curves for the attrition rate for pitchers who have not had the procedure. How many pitchers have 10 year MLB careers with or without TJ surgery?
Let's stipulate that the probability of a post-TJ pitcher having a recurrence is the same as a non-TJ pitcher having a first injury. The pitcher undergoing the procedure for the first time is much more likely to come back and resume a successful career than one who has it for the second time. In other words, the risk may not be so much in the probability of injury, but in the probability of successful recovery! While his prior TJ surgery should not disqualify Jordan Zimmermann from consideration for a free agent signing, it should factor into how much money the Giants are willing to pay him and for how long. The market may push his price to the point where it would be more prudent to invest in a lower risk pitcher or pitchers.