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MLB Rookie Report: Sean Manaea, LHP, Oakland Athletics

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Sean Manaea
Sean Manaea
Norm Hall, Getty Images

A reader asked for my current take on Oakland Athletics left-handed pitcher Sean Manaea, noting that the placement of the lefty at Number 15 on the Top 175 prospects for 2016 list was aggressive compared to rankings from other sources.

That's worth exploring, so here goes.

From the 2016 Baseball Prospect Book:

Sean Manaea, LHP, Oakland Athletics
Bats: R Throws: L HT: 6-5 WT: 235 DOB: February 1, 1992

2014: Grade B+; 2015: Grade B+

Acquired from Kansas City in the Ben Zobrist trade, Sean Manaea missed much of the first half of 2015 with muscle pulls and nagging soreness with his groin, abdominal, and oblique areas. Sidelined much of the spring, his stock had actually slipped before the trade. After the trade was another story: he got healthy and dominated the Texas League in seven starts for Midland, then posted an 11.57 K/9 with 2.10 BB/9 in 26 innings in the Arizona Fall League. When everything is right with Manaea he blows hitters away with a 90-96 MPH fastball and both his slider and change-up have above-average potential. All of his pitches were more consistent in the second half and the numbers at Midland reflect that; all told, he whiffed 90 men in 74 innings on the season. There are still some questions here, including durability and command consistency, but I’m a whore for strikeouts and will go with a Grade A-.


Manaea threw 14.1 innings in spring training before suffering a groin injury, though that's not expected to delay him very long. He posted a 4.41 ERA with a 16/7 K/BB in those 14.1 innings but he impressed spring training observers with his stuff.

There was an in-depth interview with Manaea a couple of weeks ago at Athletics Nation that is worth reading. He discusses the development of an improved change-up to go with his fastball and slider and felt that he was ahead of where he normally is at this time of year. He also discusses his Samoan background and his body/arm tattoo. There's a photo of the tattoo too.

The other big item of Manaea news this spring was a detailed scouting report published by Dan Farnsworth at Fangraphs, based on seeing the lefty pitch in the Arizona Fall League. Farnsworth pointed out the inconsistency that Manaea sometimes shows in his stuff from start to start, as well as issues keeping his mechanics in gear. Farnsworth speculated that perhaps Manaea's frequent injuries were having a negative effect.

Those are all valid concerns, but right now I'm sticking with the Grade A- and the aggressive placement on the list. There is risk here certainly, but I think the upside wins out in the end. We'll see.


Manaea has been promoted to the majors and will make the start for the Athletics on Friday, April 29th. He was off to an exceptional start in Triple-A, posting a 1.50 ERA in three starts in the Pacific Coast League with Nashville, running up a 21/4 K/BB in 18 innings. His mechanics have been very consistent since the regular season began, leading to superior command. If that remains true in the majors he will thrive immediately.

In this video, he picks up a whiff in his first start of the year.