How should the Washington Nationals replace Doug Fister's spot?

The Washington Nationals placed Doug Fister on the disabled list with tightness in his right forearm.  The 31-year-old was off to a disappointing start so far this season, with a 4.31 ERA, a 1.41 WHIP, just 4.08 K/9 and a career low 40.9% ground ball rate.  After getting lit up by the Padres Thursday night, it wasn't that big a shock to hear that Fister was dealing with an injury.  Not only has he been struggling with his command for most of this season, but he likely would have remained in the game at just 41 pitches to try and save the bullpen if he was healthy.  Already trailing 7-0, the game had kind of gotten away from the Nats early and the Nats are in the middle of a ten day stretch without an off day.  When Blake Treinen came in for the third inning, some alarm bells went off.

The Nats called rookie A.J. Cole up from Syracuse to take Fister's spot on the roster.  At first, it was being reported that Cole was coming up because the bullpen figured to be a bit undermanned with Treinen having thrown four innings and Matt Grace having thrown two innings in Thursday's series opener.  We later learned that Fister being placed on the disabled list was the corresponding move.  Ken Rosenthal reported that Cole will indeed be coming up to replace Fister in the rotation...

#Nationals viewed A.J. Cole and Taylor Jordan as initial options if starting pitcher was injured. Promoting Cole to replace Fister.

— Ken Rosenthal (@Ken_Rosenthal) May 15, 2015

Cole did have an ugly debut last month when he came up to replace Max Scherzer for a start in Atlanta.  In a game that some believe turned the Nats early season slide around, Cole allowed nine runs (four earned) in just two innings against the Braves.  Of course, the Nats came back with a stunning 13-12 win on Dan Uggla's three run homer in the ninth inning.  We probably shouldn't put that much stock in that appearance for Cole.  It was his debut.  The adrenaline might have been flowing a bit too much.  His command seemed way off from what we were led to expect it to be.  Everything was up and he got tagged.

Cole has looked fine in two starts since returning to Syracuse.  The 23-year-old right hander went six innings in each of those outings, allowing just four runs on ten hits and a walk.  Cole also looked comfortable in his return to the majors Friday, throwing the final three innings of a 10-0 laugher against the Padres as he earned his first big league save.  He attacked the zone, throwing 23 of his 37 pitches for strikes.  He was able to avoid the dreaded middle-middle pitches that Fister threw an awful lot of on Thursday as well.  Cole ended up allowing just one hit without walking anyone and struck out one in the outing.

Should we make anything of the fact that Cole was used out of the bullpen Friday?

Nope.  Cole was on regular rest Friday, so he took his usual turn in the majors instead of the minors throwing just three innings in a blowout win.  The Nats have Monday off, so Fister's spot won't come up in the rotation again until Wednesday.  This would again be regular rest for Cole after he threw three innings Friday.  With the long men in the bullpen taxed in Thursday's game, they had a need for someone to go multiple innings anyway.  To be honest, with two off days this week, the Nats could actually avoid having to use a fifth starter until May 26.  In other words, it's possible that nobody is the fifth starter for the next week and a half.

Should the Nats be going to A.J. Cole over Tanner Roark or Blake Treinen?

This is the big question.  The severity of Fister's injury may be the determining factor.  We've seen many forearm strains turn out to be associated with the Ulnar Collateral Ligament.  Even casual baseball fans know that a torn UCL is what leads to Tommy John surgery.  Let's not jump to conclusions, though.  Players do have strained forearms without it leading to the worst case scenario, so we won't know much about the severity of Fister's injury for at least another couple of days (maybe not until he resumes throwing).  Before we break down whether or not this is the right call, let's take a look at the three (four?) candidates.

Tanner Roark

Roark seems to be the obvious call for the Nats if they expect Fister to miss extensive time.  Roark was displaced to the bullpen after the Max Scherzer signing, but had an outstanding first full season in the rotation last season.  The 28-year-old had a 2.85 ERA (3.47 FIP) last season in 198.2 innings of work and the assumption is that he'll return to the rotation next season assuming either Fister, Jordan Zimmermann, or both depart via free agency.  There would appear to be two potential issues with immediately installing Roark into Fister's spot in the rotation:

1. He's not stretched out.  Roark has made two three inning appearances this season out of the bullpen, but his most recent extended appearance occurred on April 28.  It will take at least a few outings before he can build his arm strength up to throw the workload typically expected of a starting pitcher (90-110 pitches)
2. Injuries to Craig Stammen and Casey Janssen (seems close to returning) have demanded that Roark take on a larger role than initially anticipated in the bullpen.  The Nats don't have very many experienced pitchers in the bullpen right now, and a few of the kids (well... mainly Treinen) haven't performed well in high pressure/leverage spots

If Fister's injury is indeed a short-term issue, it's going to take Roark almost as long to build up to throwing a normal starter's workload as it will for Fister to return.  If the forearm tightness is a precursor to something else, they should probably send him to Syracuse when Casey Janssen returns to gradually build up to throwing a starter's workload again.  He does have minor league options remaining, so sending him to AAA is in play.

Blake Treinen

Treinen would have one of the same issues that Roark has.  He did throw a season high 57 pitches on Thursday in relief of Fister, but it would likely take a few outings in Syracuse for him to build up to a normal starter's workload.  He hasn't looked great when thrust into leverage spots in the bullpen, and I've complained about his struggles against left-handed hitters several times already.  He'd likely see more lefties as a starter.  Unlike Roark, Treinen's future in the organization appears to be in the bullpen.  He has big splits.  He relies primarily on two pitches (sinker/slider), which profiles better as a reliever.  It's tough to turn a lineup over multiple times without at least a third pitch.  The Nats have already made the move to turn him into a reliever.  They should probably leave him there.

A.J. Cole

Cole got the call, so it appears he'll be the obvious choice over the other minor league starter they might have considered (Taylor Jordan).  Among their minor league starters, Cole appears to have the best mix of ceiling and readiness.  He certainly doesn't have the ceiling of a pitcher like Lucas Giolito (probably not Reynaldo Lopez either), but both Giolito and Lopez just recently reached A+ ball in Potomac.

Cole has thrown 90 innings in AAA ball over the past two seasons and 224 innings in the "high minors" (AA or higher) with quite a bit of success.  Depending upon whom you believe, Cole has either the second (behind Giolito) or third highest (Giolito and Lopez) ceiling among minor league starters in the system.  He appears more likely to have a future in a big league rotation than any of their other starters in the high minors.  The more veteran starters in AAA (Bruce Billings, Taylor Hill, Jordan, Scott McGregor) are less exciting, and only Cole, Hill, and Jordan are on the forty man roster.  Cole seems like the clear choice among those options.

Taylor Jordan

Jordan is off to a pretty nice start in Syracuse (2.45 ERA, 2.56 FIP in 33 innings), but he's more of a fringe guy than Cole.  While Cole looks like he may develop into a middle of the rotation starter, Jordan is more of a back end starter/swing man.  I do feel that Cole should be getting a regular starter's workload for most of this season before presumably being given a shot to compete for a rotation spot in 2016.  If those starts become temporarily available at the big league level, it's fine to bypass Jordan for Cole.  Cole could probably use a little more time to refine his command at the AAA level, but he's also going to learn a bit more by facing the best hitters in the world in the majors.

Get creative?

With Treinen having struggled to get comfortable in shorter outings (more high leverage, but shorter as well), why not try piggybacking/tandem starting Cole and Treinen?  After throwing four innings on Thursday, Treinen likely isn't going to be available until Tuesday anyway.  If the Nats choose not to skip the fifth spot in the rotation this week and start Cole on Wednesday, they could set a limit on Cole's pitch count and have Treinen ready to throw two or three innings behind him.  If the news after Fister's exam in D.C. isn't good, they could simply make Tanner Roark the tandem starter with Cole instead of Treinen to help Roark gradually build up towards throwing higher pitch counts.  Cole could adjust more gradually to the big league level while the Nats' long man (Treinen) or long-term replacement for Fister (Roark) could stretch themselves out a bit more.

Let's hope this is just a short term thing, though.  A.J. Cole with Blake Treinen backing him should do fine for a few weeks.  Hopefully Fister is back, healthy, and treating us to two hour ballgames again soon.