Excluding a select few bullpen iron men like Mariano Rivera and Trevor Hoffman, relievers just aren't built for sustained excellence. Their job -- hurling max-effort pitches, logging what amounts to two months' worth of innings for a starter -- is inherently volatile. Some 'pen arms manage to dominate for a decade-plus, avoiding injury and bad bounces that balloon ERAs, but many more devolve from relief ace to dud quicker than you can say "Derrick Turnbow."
Fernando Rodney hasn't quite fallen to such depths -- he just landed a two-year, $14 million contract from the Mariners, after all. But he's nonetheless a prime example of how transient the "relief ace" label can be. The changeup artist was considered a chronic underachiever entering the 2012 season, posting a career park-and-league-adjusted ERA just one percent above average (101 ERA+) and issuing 4.9 walks per nine innings pitched. Then Rodney, in his mid-thirties, suddenly became an arrow-slinging assassin. He walked a mere 1.8 hitters per nine for Tampa Bay in 2012, with the best single-season ERA+ (638) ever for a reliever working 60-plus frames. After a decade of disappointment, Rodney turned in a year that made Dennis Eckersley's fabled 1990 campaign (603 ERA+) look tame.
Was Rodney a changed man? Apparently not. While no one should have expected a repeat performance of 2012, he was pretty much the same strike zone-challenged pitcher who unnerved fans in Detroit and L.A. for a decade (4.9 BB/9, 113 ERA+ with Tampa in 2013). Left-handed batters proved especially troublesome. While lefties took wild swings against his fastball/changeup combo during his banner 2012, they learned to lay off and trot to first base in 2013.
Rodney enticed lefties to chase his pitches 38.9 percent of the time in 2012, blowing away the 28 percent average for righty relievers against opposite-handed batters and trailing only Red Sox teammates Koji Uehara (48.3 percent) and Junichi Tazawa (39.4 percent) among American League firemen. In 2013, though? Rodney baited lefty hitters 31.3 percent of the time, which matches his overall lefty chase rate during the Pitch F/X era (2008-present).
What changed? Lefties stopped bailing Rodney out by swinging at pitches so far off the outside corner that they'd need a telephone pole to make contact. Check out lefties' swing rate by pitch location versus Rodney's fastball over the past two seasons, and then against his changeup.
Rodney's fastball chase rate against lefties dipped from 33.7 percent in 2012 to 24.7 percent this past season. That's awfully close to his overall 26.8 percent fastball chase rate versus left-handers during the Pitch F/X era. He also got fewer chases on the changeup: 47 percent in 2012, and 39.7 percent in 2013. His changeup chase rate against lefties since '08? 39.1 percent. With lefties showing more typical plate patience against him, Rodney surrendered a free pass to 15.2 percent of batters faced after walking lefties just 6.3 percent the previous season. Lefties reached base at a .363 clip, after being held to a .222 OBP in 2012.
Rodney will always have 2012, but he doesn't appear to be a fundamentally different pitcher than the guy who gave Jim Leyland and Mike Scioscia heart palpitations for years. Unless lefties do him a favor by lunging at unhittable, off-the-plate pitches, Seattle's new crooked-capped closer figures to keep walking the yard.