Johan Santana is twice a Cy Young award winner and four times an All-Star. Since he became a full-time starter in 2004, Santana has never finished a season with an ERA higher than 3.33. Not even Greg Maddux in his prime could say that (although he came very close).
For a while now, Santana has been regarded as one of the elite pitchers in Major League Baseball. Most put him in the top-five best starters in the game; the rest in the top-ten. Given his 2.89 ERA this year, most will continue to put him atop these lists and he will mostly be drafted within the top seven rounds next year.
For the Sabermetrically-inclined, however, there are a lot of warning signs that should scare you, especially if you have him in a keeper league.
In 2007, the final year with the Minnesota Twins, Santana finished with a K/9 at 9.7. During the off-season, he signed a six-year, $137.5 million contract extension with the New York Mets following a trade. By all accounts, he had a great '07 season, but his K/9 dipped to 7.9 and he lost 1.5 MPH on his average fastball speed from '06 to '07. Both nuggets of information went relatively unnoticed. Those who did take note usually labeled it a fluke.
After spending a few years at or near the top of the SIERA leaderboard, Santana barely cracked the top-20 in the Majors in '08, sitting at 3.59. His average fastball velocity continued to drop.
That brings us here, to 2010. Santana has experienced more success with a 2.89 ERA. Yet Santana's K/9 has fallen precipitously to 6.4. His average fastball velocity is now below 90 MPH. According to the pitch type linear weights on FanGraphs, Santana's change-ups the past two seasons have been the least valuable they have ever been in his illustrious career.
Santana's current 4.31 SIERA ranks 77th among pitchers with at least 100 innings of work. He is just ahead of Doug Fister. If you had told the Mets organization, before they completed that trade with the Twins and dotted the i's on that six-year contract extension, that Santana would perform as well as Doug Fister in 2010, Omar Minaya would have exited the conference call quicker than Usain Bolt.
The good news is that you do not owe Santana at least $77.5 million through 2014. You simply have him on your fantasy team(s). Obviously, there are a few red flags as mentioned. His K/9 has dropped from 9.7 in 2007 to 6.4 here in '10. In the same span of time, his fastball lost 2.3 MPH; his slider 3.1 MPH; and his change-up 2.5 MPH. According to FanGraphs, his fastball and slider are as straight as they have been in the Pitch F/X era. And there's his ever-increasing SIERA.
Johan Santana is not a player you just kick the curb, especially with the run of success he has had this season. You have to keep him on your roster and hope for continued success unless you can include him in a trade. The trading deadline is quickly approaching in most leagues. The less Sabermetrically-inclined your opponents are, the more likely you can unload him and get back useful players.
Or you could simply hope he continues to evade his SIERA. He has done it thus far this season. By statistical nature (and because we are not all-knowing beings), there will be pitchers who vastly outperform their SIERA and Santana could be one of them. With the Mets' above-average defense (both infield and outfield) and pitcher-friendly home park, Santana has a better shot at outrunning those pesky ERA estimators.
In neither scenario — retaining or relinquishing — are you 100 percent comfortable. In one, you are trying to unload a two-time Cy Young winner who has been among baseball's best so far this season. In the other, you are standing pat with a pitcher who has performed about as well as Doug Fister, though with very different results. It is a tough decision but it could make or break your keeper team's future, depending on where you find yourself in the standings. Getting rid of Santana could mean the difference between future contention and irrelevance.