Who Is the Oakland A's Best Reliever?

We're only four games into the 2016 Oakland Athletics season and there is already one notable difference from last year's squad: the bullpen.

The Oakland front office invested tens of millions of dollars and one Jesse Chavez in a revamped corps of late inning relievers. While Chavez would look mighty fine as the team's fifth starter right about now (or third or fourth starter for that matter), the improvement in the bullpen is undeniable and has been an encouraging sight thus far.

However, this isn't to say that the bullpen hasn't had its hiccups. One Jimmy Rollins home run and one really, really bad inning in Thursday's game are the only real blemishes from the relievers on this young season.

Overall, when the game is turned over to the bullpen there is hope where there was once none. Which leads to the question: who is the A's best reliever?

The candidates:

Sean Doolittle

The former first base prospect endeared himself to fans both with his high heat and his generosity and friendliness off the field. Since he entered the big leagues in 2012 Doolittle is tied for 10th in the league with 5.8 fWAR, his 2.31 FIP is 9th best, his 25% K-BB% is tied for 9th, and he has 29 saves and 50 holds. Those totals include his 2015 which was a lost season for Doolittle due to injuries. Even if his stuff isn't quite "as good" as it once was, Doolittle has the opportunity to be a better pitcher than ever with his changing repertoire.

John Axford

It's a little strange to see a reliever with an ERA higher than 4.00 in three of his last four seasons get a multi-million dollar contract. That is what happened when the A's made a somewhat unpopular choice in giving John Axford a two-year deal for $10 million. The film aficionado has baseball's 20th-best average fastball velocity among active players since 2009, according to PITCHf/x. He's 23rd in baseball with a 10.59 K/9 over that same timeframe while posting other strong peripheral numbers. He has also accumulated the 9th most saves with 141 since 2009.

Ryan Madson

The elder statesman of the Oakland bullpen, Madson has long been one of baseball's finest relievers. His 6.8 fWAR is 17th best among active relievers since 2007 and his 2.76 ERA is 27th best. He throws two quality fastballs along with an excellent changeup and will be Oakland's go-to setup man in 2016. HE was even called on to save Oakland's first win of the season when Doolittle was unable to pitch. The A's gave him a three-year contract because he is expected to remain among baseball elite late-inning relievers.

Liam Hendriks

Some chatter on the Athletics Nation comment threads has revealed some of you think Hendriks might just be Oakland best relief pitcher. You might be correct about that, despite his late game struggles Thursday. Until 2015 Hendriks had primarily been a starting pitcher and not a very good one. He posted low strikeout rates and high home run rates despite pitching most of his innings in the friendly homes of the Minnesota Twins. Last season the Toronto Blue Jays converted him to a short-inning reliever and something clicked. It is well known that in shorter stints pitchers often find their velocity is much higher. That was certainly true for Hendriks who gained at least 3 MPH on each one of his five pitches, per PITCHf/x. His repertoire includes three above average pitches per PITCHf/x: four seam fastball, slider, and changeup. His 1.5 fWAR tied him for 16th best in baseball among relievers. One of his big improvements was in his ability to miss bats and limit walks. His 23% K-BB% was good for 21st in baseball.

Fernando Rodriguez

He was the only positive contributor to Oakland's bullpen in 2015, which is a big reason why he returned to the bullpen in 2016. He was a throw-in when the A's first acquired Jed Lowrie in 2013. Injury cost him all of 2013 and he pitched just 9 innings in 2014, but his 2015 was a relative success. His K/9 nearly reached 10 in almost 60 innings and his 3.08 FIP was stellar. He doesn't offer up too many home runs but walks are a problem as his career BB/9 is 4.27. Still, a reliever with a fastball that reaches mid-90s who strikes out more than a batter per inning is much more than you need from your fifth or sixth best option.

Ryan Dull

He clearly isn't Oakland's best reliever, but I wanted to mention him here because he has looked very good so far this season, despite barely making the team out of spring training. Dull was exceptional in Double-A in 2015 posting a 10.40 K/9 and a minuscule 0.60 ERA. It's hard to believe he got even better in his brief Triple-A stint but he did. In 16 innings with the Nashville Sounds Dull struck out more than 34% of batters he faced and walked less than 5%. He stranded just about 95% of batters on base and almost never gave up a home run. He doesn't throw harder than others (averaging low-90s with his fastball) but a deceptive delivery and excellent control make him a truly exciting up-and-comer in the Oakland bullpen.

Conclusion

Doolittle is returning to the closer role after injuries cost him nearly all of 2015, and that should stabilize the bullpen. However, should injuries crop up again or he shows ineffectiveness (doubtful) the A's have several others poised to be quality replacements when there wasn't one last year. That brings me back around to my earlier question: Who is the best Oakland reliever?

I think Madson is the best reliever of the bunch. He has enough of a strikeout ability to get get swings and misses when needed, but his ability to get ground balls more than 50% of the time should allow him to induce timely double plays and avoid home runs. Doolittle and Hendriks are close behind, but I've really enjoyed what Axford, Rodriguez, and Dull have shown which could make this question hard to answer as the season goes on. What do you think?