The Oakland A’s shuffled their bullpen on Saturday with the announcement of several moves. The biggest news is that Santiago Casilla was designated for assignment, and right-hander J.B. Wendelken was called up to take his spot on both the 25-man and 40-man rosters. In addition, reliever Ryan Dull was optioned to Triple-A Nashville, and infielder Franklin Barreto was called up to replace him. Finally, starter Daniel Mengden was activated from the disabled list and optioned to Triple-A.

Let’s begin with the positive news, as Wendelken returns to Oakland for the first time since 2016. He made his MLB debut that year for the A’s, but after the season he went down with Tommy John surgery. Now the 25-year-old is back in action, and his numbers are better than ever. He started the summer with a brief stint in Double-A, but he quickly made his way up to Triple-A in May and appeared in 17 games. His 38.1% strikeout rate is fourth in the Pacific Coast League (min. 20 innings).

Wendelken, 2018 AAA: 3.49 ERA, 28⅓ ip, 45 Ks, 8 BB, 2 HR, 2.36 FIP

Prior to his surgery, the right-hander’s signature pitch was a devastating changeup — see the video at the bottom of this post. Here’s a scouting report from before the 2016 season, when he was acquired in the Brett Lawrie trade. His first taste in the bigs that year resulted in an enormous 9.95 ERA (6.46 FIP) thanks to a few ugly outings while performing mop-up duty, but he also mixed in several impressive showings as well.

On the way out is Casilla, who is nearing the end of his two-year contract. He was mostly ineffective during his stint with the A’s, and appeared to be relegated to garbage time at this point. In 2017 his 4.27 ERA was league-average but he blew 7-of-27 save/hold chances, and this year his walk rate was outrageous. On the surface his ERA looked good this summer, but everything about the rest of his stats suggested it was a mirage. His line was the definition of “effectively wild.”

Casilla, 2018: 3.16 ERA, 31⅓ ip, 22 Ks, 20 BB, 0 HR, 18 hits, 4.03 ERA

The 37-year-old last appeared Friday night against the Giants. He entered with the bases loaded and the game still potentially within reach at 4-1, but he allowed all three inherited runners to score on a sac fly, a wild pitch, and a double. Overall he allowed 5-of-9 inherited runners to score this season, and 9-of-15 total during his contract. Susan Slusser of the S.F. Chronicle notes that it’s unlikely Casilla will be claimed on waivers, and that “then it will be his decision if he wants to accept a minor-league assignment if offered.”

Also heading out is Dull, who pitched in three games since coming up on Tuesday. The first two went well, as he threw a scoreless inning that evening and another on Wednesday in a pair of competitive contests against the Astros. However, the third one went poorly in a close affair Friday night against the Giants. He entered to start the 7th facing a one-run deficit, and loaded the bases with a pair singles and a walk to the first (and only) three batters he faced. When the dust settled, the Giants had scored six runs and put the game out of reach.

Dull, 2018: 6.00 ERA, 18 ip, 17 Ks, 5 BB, 3 HR, 21 hits, 4.25 FIP

It’s been a tough year for Dull, who has struggled to find consistent success in the bigs since his breakout 2016 campaign. With his return to Nashville, the A’s bullpen is now down to its normal eight members.

With two relievers going out and only one coming up, the other spot goes to Barreto. All-Star second baseman Jed Lowrie left Friday’s game after colliding with right fielder Stephen Piscotty while chasing a fly ball. Lowrie suffered a bone bruise and calf bruise on his left leg, reports Steve Kroner of the S.F. Chronicle. He’s not in the lineup Saturday but feels good enough that he’s available if needed, reports insider Jane Lee. In the meantime, Barreto can provide some insurance in the infield just in case.

Barreto, 2018 (54 PAs): .212/.241/.442, 83 wRC+, 3 HR, 1.9% BB, 42.6% Ks

Since returning to Nashville from his last MLB stint, Barreto played seven games and went 4-for-20 with three dingers and six walks, but he also struck out 10 times in 29 plate appearances. That’s been the story of his season so far — way too many Ks, but great results when he does make contact and a spike in walk rate that offers hope the 22-year-old’s batting eye might be slowly improving. His time in MLB has been the same, with tons of whiffs but occasional glimpses of his dynamic speed and power.

In one final move, Mengden was activated from the DL. He last pitched June 23 but left with a sprained foot, and after two minor league rehab outings he’s ready to go. However, the A’s don’t need a fifth starter again until after the All-Star break, so he’ll stay in Triple-A for now.

Hot takes

Finally. With the A’s suddenly facing a chance at contention, it was time for them to get serious about their bullpen. That means trimming some of the unreliable arms and trying out the impact prospects toiling in Triple-A, rather than prioritizing the retention of maximum depth.

With respect to Casilla, he was no longer helping the team but his continued presence meant that they’d have to turn to him now and then in an important moment. Now they can move forward and see what they’ve got in Wendelken, who has more than earned his next chance. Chris Hatcher still remains as a weak link, and top relief prospect Bobby Wahl still waits in Triple-A, but at least this is one big step forward by removing one of the deadweight arms who couldn’t be relied on in the late innings but also couldn’t be freely optioned to the minors.

Here’s the updated roster:

Oakland A's 25-man roster Pitchers Hitters Starters



Sean Manaea (L)

Edwin Jackson (R)

Trevor Cahill (R)

Brett Anderson (L)



Relievers



Blake Treinen (R)

Lou Trivino (R)

Ryan Buchter (L)

Yusmerio Petit (R)

Emilio Pagan (R)

Chris Hatcher (R)

J.B. Wendelken (R)

Jeremy Bleich (L) Catchers



Jonathan Lucroy (R)

Josh Phegley (R)



Infielders



Matt Olson (L)

Jed Lowrie (S)

Marcus Semien (R)

Matt Chapman (R)

Franklin Barreto (R)



Outfielders



Khris Davis (R)

Stephen Piscotty (R)

Dustin Fowler (L)

Mark Canha (R)

Chad Pinder (R)

Nick Martini (L)

10-day DL: RHP Paul Blackburn (elbow), RHP Daniel Gossett (elbow), OF Matt Joyce (back)

60-day DL: RHP Jharel Cotton (TJS), RHP Andrew Triggs (triceps/nerve), OF Boog Powell (knee)