Mariners News: Top Prospect Edwin Diaz Moved to Bullpen

The Mariners reigning Minor-League Starting Pitcher of the Year is moving to the ‘pen.

Edwin Diaz is unanimously ranked as the Seattle Mariners’ top minor-league pitching prospect. The 22-year-old right-hander represented the M’s at last season’s Futures Game, and he is dominating with the Jackson Generals in 2016.

Dipoto confirms that Edwin Diaz has been converted to a reliever
— Ryan Divish (@RyanDivish) May 11, 2016

However, it was announced on Tuesday night that Diaz will shift from the starting rotation to the bullpen. Rumors began circulating on Monday, but Jerry Dipoto confirmed the news last night.

The Puerto Rican native is dazzling with the M’s Class-AA affiliate in Jackson this season, going 2-3 with a 3.00 ERA across 7 appearances (6 starts). Diaz has struck out 40 and walked 5 through 30 innings of work. He has limited the opposition to just 1.133 walks/hits per inning.

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The former third round pick split the 2015 season between the Bakersfield Blaze and the Jackson Generals. Diaz started the year in the California League, and he was electrifying. He went 2-0 with a paltry 1.70 ERA across 7 outings. Diaz fanned 42 and issued just 9 free passes in 37 innings pitched. He also limited the opposition to 0.811 walks/hits per inning.

Diaz’s remarkable performance in Bakersfield prompted the M’s to promote him to Jackson. Diaz pitched well with the Generals, but he was unable to duplicate the numbers he posted in the California League. He went 5-10 with Jackson, and registered a 4.57 ERA across 20 starts. He stuck out 103 and walked 37 through 104.1 innings.

Combined, Diaz went 7-10 with a 3.82 ERA in 27 starts last season. He led all Mariners’ minor-leaguers with 145 strikeouts in 2015, and placed 9th in all of minor-league baseball by averaging 9.2 strikeouts per 9 innings. He has excellent command of his arsenal, and he issued just 2.9 walks per 9 innings last year. Perhaps most impressive of all, Diaz limited the opposition to a dismal .237 batting average across 141.1 innings of work.

On the surface, this move seems like a head scratcher. However, there are a couple reasons why this transition makes a ton of sense. Diaz is undersized for a starter at 165 pounds, and some have questioned his ability to stay healthy over the course of a full season. Another issue is his lack of a third pitch. Diaz utilizes a remarkable fastball/slider combo, but his changeup is subpar at best.

Dipoto had this to say regarding the decision to move Diaz to the bullpen:

"We felt like he had the potential to be a Major League starter, but he had the potential to be an impact Major League reliever. To me, one supersedes the other."

A number of teams have had success using starting pitching prospects as relievers in recent seasons. None more so than the Toronto Blue Jays. Aaron Sanchez spent the bulk of his first two seasons working as a reliever, and Roberto Osuna has been one of the top closers in baseball. Hopefully the Mariners can get similar results from Diaz this season.

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I’m sure Edwin Diaz was not thrilled to hear that he will no longer be working as a starter, but this could be a blessing in disguise. The Mariners already have a veteran pitching rotation, and James Paxton is waiting in the wings in Tacoma. Diaz likely would not have debuted in Seattle before 2017 as a starter, but as a reliever, I think we could see him toe the rubber at Safeco this summer.

Scouts believe that Diaz’s fastball and slider are big league ready, but his body is not there yet. Working as a reliever will give him some time to mature physically and work on his changeup. Diaz could return to the rotation in the future, but I believe he has a chance to develop into a closer or a setup man in Seattle.

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Look for Diaz to be promoted to Tacoma in the next couple weeks. If everything goes well with the Rainiers, Diaz could be in the Emerald City as early as July.

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