clock menu more-arrow no yes mobile

Filed under:

A’s bullpen looks like a strength again in 2021 after late barrage of additions

It might be even better than 2020

National League Division Series Game 3: Los Angeles Dodgers v. San Diego Padres Photo by Kelly Gavin/MLB Photos via Getty Images

The Oakland A’s arguably had the best bullpen in the majors in 2020. They led the sport in ERA, ranked third in FIP, second in Win Probability Added, second in bWAR, and fifth in fWAR. They only blew the lead four times, second-fewest in the bigs.

That 2020 group was led by closer Liam Hendriks, who was named AL Reliever of the Year, as well as three setup men — Joakim Soria, Yusmeiro Petit, and All-MLB Team finalist Jake Diekman. Behind them were a slew of arms providing solid work, somewhere between decent and excellent, like J.B. Wendelken, Lou Trivino, T.J. McFarland, Jordan Weems, and Burch Smith.

Unfortunately, that dominant unit was torn apart by free agency. Four key names came off the roster, including Hendriks, Soria, Petit, and McFarland. There was still some quality talent left over, and room to make additions, but a serious revamp was coming whether from in-house or externally.

By the beginning of February, not much had happened. Oakland had picked up a sleeper lefty in Nik Turley, whose future is more interesting than his past, and they’d made a Rule 5 draft pick in Dany Jimenez. Personally I like going cheap on a bullpen, but they looked like they were really going for it in that regard.

And then, the A’s suddenly went on a mid-February spree. They’d always said they were going to wait out the market, plus they’d picked up some extra cash in their Elvis Andrus trade, and when they struck it was spectacular. They made another trade and then nabbed three good free agents, including one of their own in Petit, and suddenly their bullpen went from thin to stacked.

Here’s the new depth chart. In the first tier, those who played in MLB last year and are now on the 40-man roster.

  • RHP Trevor Rosenthal, closer
  • LHP Jake Diekman, setup
  • RHP Yusmeiro Petit, setup
  • RHP Sergio Romo, setup
  • RHP J.B. Wendelken (out of options)
  • LHP Adam Kolarek
  • LHP Nik Turley (out of options)
  • RHP Dany Jimenez (Rule 5 pick)
  • —RHP Lou Trivino
  • —RHP Burch Smith
  • —RHP Jordan Weems

That’s 11 pitchers for eight spots, and Trivino, Smith, and Weems each have options remaining. That means there’s depth for injuries in the spring or early summer, or for if Jimenez doesn’t work out this spring and misses the cut for the Opening Day roster.

Next tier, prospects on the 40-man roster who are currently starters but could potentially end up in the bullpen at some point in 2021. Each of them ranks Top 10 on our Community Prospect List, and they all have options remaining.

  • LHP A.J. Puk
  • RHP Daulton Jefferies
  • RHP James Kaprielian
  • RHP Grant Holmes (hasn’t yet debuted in MLB)

Next tier, relievers who are on the 40-man but haven’t debuted in the majors.

  • RHP Wandisson Charles
  • RHP Miguel Romero

Final tier, non-roster invitees who have MLB experience, in order of career innings. If they win a job out of spring, then a move will need to be made to add them to the 40-man.

  • RHP Deolis Guerra
  • RHP Brian Schlitter (re-signed for third year in A’s org)
  • LHP Reymin Guduan
  • RHP Montana DuRapau

The extent of that list is far more than we need for the Opening Day conversation, but it gives an idea of what kind of depth is available behind that primary group. And it’s an impressive primary group.

One way to look at it is a comparison with last year. The update works out like this.

2020 2021
Hendriks Rosenthal
Diekman Diekman
Soria Romo
Petit Petit
Wendelken Wendelken
McFarand Kolarek

Of those top six names, half of them are returning. That doesn’t mean Diekman, Petit, and Wendelken will each be as good as they were last year, but all you can ask is to get the same player back for another try, and there is every reason to believe this trio will keep chugging.

And the three replacements?

Kolarek vs. McFarland

We’ll begin with Kolarek vs. McFarland. Both are lefties whose game plans primarily focus on inducing massive rates of ground balls, rather than strikeouts or big velocity, and both are more effective against lefty hitters. A few select career rates (league average xwOBA is in the .320ish range):

  • Kolarek: 3.32 ERA, 3.87 FIP, 16.8 K%, 62.7 GB%, .282 xwOBA
  • McFarland: 4.08 ERA, 4.15 FIP, 13.6 K%, 62.8 GB%. .327 xwOBA

They’re similar in style, but Kolarek is clearly more successful. His run prevention is better both in reality and in theory, he gets as many grounders but with more strikeouts, and Statcast prefers him by a lot. The difference is even more pronounced in 2020 alone, where Kolarek was far and away the superior performer.

  • Kolarek, 2020: 0.95 ERA, 3.14 FIP, 18.1 K%, 63.0 GB%, .250 xwOBA
  • McFarland, 2020: 4.35 ERA, 6.34 FIP, 9.8 K%, 59.7 GB%, .355 xwOBA

Oakland effectively upgraded this bullpen spot, the middle-inning lefty groundball specialist, from replacement-level to another serious weapon.

Romo vs. Soria

Next up is Romo vs. Soria, which is much more comparable. Both are former closers in their late-30s who have now settled in as durable setup men, and they’ve put up similar work over the last two seasons. Can you tell them apart, in a similar number of innings in 2019-20, both striking out more than a batter per frame?

  • Player A: 3.94 ERA, 3.46 FIP, 3.43 K/BB, .280 xwOBA
  • Player B: 3.59 ERA, 3.84 FIP, 3.46 K/BB, .280 xwOBA

They may as well be clones, and Statcast literally can’t tell the difference. Player A is Soria, with the edge in FIP but the worse ERA. Player B is Romo, and he also had a huge edge in Win Probability Added and piled up nearly twice as many save/holds (52 Romo, 28 Soria) with the same number blown (6). Soria’s low/mid-90s fastball, or Romo’s wicked slider, six in one, half dozen in the other.

If anything, Romo gets the edge here, for two reasons. He saw even more late-inning action lately than Soria did (not to mention some opening experience in the 1st inning), and he relies even less on velocity as they both creep further into their decline phases.

Rosenthal vs. Hendriks

That leaves Rosenthal vs. Hendriks, and there’s no way we’re going to conclude that the A’s upgraded from the current best reliever in the sport. But if you can’t have the best, then you can at least get as close as possible.

Rosenthal is about as close as possible, if you believe in his 2020 re-breakout. He’s a former All-Star who went through Tommy John surgery and a wonky 2019 return season, but let’s do another blind comp and see how different he really was from HercuLiam last summer.

  • Player A: 1.78 ERA, 1.14 FIP, 40.2% Ks, 12.33 K/BB, .227 xwOBA, 1 blown save
  • Player B: 1.90 ERA, 2.22 FIP, 41.8% Ks, 4.75 K/BB, .210 xwOBA, 1 blown save

They threw around the same number of innings, serving as closers who put up double-digit saves. The biggest difference is that Player A, Hendriks, had a walk rate that was amazing instead of just good. Statcast actually liked Rosenthal more, and he also throws harder by two full miles per hour.

Sure, Rosenthal’s most recent success came in a tiny sample, but it at least showed he’s back to form in general after his 2019 yips. And it’s not like Hendriks has a long track record of stardom either, around 110 frames over the last two seasons.

If I could start a bullpen right now with any one reliever, I’d choose Hendriks. But we can’t do that here because he costs $54 million. So if I were to instead put together a list of the top five or 10 candidates most likely to dethrone Hendriks as the king in 2021, then Rosenthal would be on it. It’s a downgrade, but a smaller one than we ever imagined it would be.


Of the top three relievers the A’s lost to free agency, they significantly upgraded on one, matched or slightly upgraded another, and took only a minor downgrade on the biggest star.

Of course, these are relievers we’re talking about, so not everybody will be exactly who they were last year. Even if Diekman is great again, he’ll give up more than one run every two months. And even if Rosenthal is better than Hendriks next year, he still probably won’t fully repeat Liam’s absurd 2020.

But an area that looked like it might turn from a primary strength into a crucial question mark instead stayed every bit as strong as it was before. There’s an Almost Hendriks closing, basically the same setup crew, an upgrade in the middle ranks, and increased heaps of premium depth that should help account for whatever inevitably goes wrong along the way.

Did the bullpen get even better than last year’s top-ranked unit? At the very least, it didn’t get worse, even without Liam Hendriks.