The Mariners recently lost starting pitcher Hisashi Iwakuma to free agency when Iwakuma signed with the Dodgers for three years and $45 million. Wade Miley will slot into the starting rotation behind Felix Hernandez along with Taijuan Walker, James Paxton, and Nate Karns. Miley essentially replaces Elias in the Mariners’ starting rotation, so let’s compare the two.
Wade Miley has pitched 190 or more innings in each of the last four years and has a career ERA of 3.95 and a career WHIP of 1.33. His best year was in 2012 when he had an ERA of 3.33. Over the last two years, his ERA has been 4.40 but his Fielding Independent Pitching (FIP) over that time lines up with his career ERA, in the range of 3.90. He can be expected to have an ERA around 4.00 and might be even better because Safeco Field is a better park for left-handed pitchers than Fenway. I could see a 3.75 ERA with the Safeco Field effect and a better defense behind him.
Roenis Elias has pitched 163.7 and 115.3 innings over the last two years and has a career ERA of 3.97 and a career WHIP of 1.31. Based on FIP, though, he’s more like a 4.25 ERA pitcher. He also hasn’t been as durable as Miley, but he is two years younger.
The projections for 2016 suggest there isn’t a great deal of difference between Miley and Elias, other than the expected number of innings pitched:
The other part of this deal involves a minor league pitcher coming to the Mariners and high-strikeout relief pitcher going to the Red Sox. The high-strikeout relief pitcher is Carson Smith. In 78 1/3 major league innings, Smith has struck out 32.6% of the batters he’s faced. That’s slightly better than Chris Sale this year (32.1%). Of course, Smith did it as a late-innings reliever in short stints, but it gives you an idea of his ability to miss bats. He is elite in that regard. His walk rate is fine and he has only allowed two home runs in his career. Those are the three things a pitcher has the most control over and they show Smith to be a dominant arm. He has a career 2.07 ERA (2.09 FIP) and picked up 13 saves when he was put into that role last season. Frankly, I’m shocked the Mariners would part with Smith. He was their best relief pitcher last season and seemed destined for a key late-inning role in next year’s bullpen.
Jonathan Aro is a relief pitcher with a career 2.83 ERA in 301 2/3 innings, with a strikeout rate of 8.7 and a walk rate of 2.2. He’s not any sort of highly-rated prospect and is most likely to be a middle reliever who may start next year in AAA and come up at some point during the season.
Overall, I’m not impressed with this trade. I think Elias has a chance to be just as good as Miley and the combination of Elias and Carson Smith will be better and cheaper than Miley and Aro over the next few years. Miley is a safer arm to have in the rotation than Elias, but there’s no guarantee that he’ll be un upgrade.