Leave it to the Yankees to make the first big move of the offseason. 

The Mariners had already been busy, reacquiring Mallex Smith from the Rays in exchange for Mike Zunino. But by pulling the trigger on Monday's James Paxton deal, which landed them exactly one noteworthy prospect in Justus Sheffield, they may have jump-started the trade market, taking one of the biggest chips off the table before Thanksgiving.

Fantasy owners would obviously prefer Paxton pitch for a winner than a loser, which is what the 2019 Mariners are shaping up to be. So in the strictest sense, this trade is good for his Fantasy value. From the perspective that he was likely to be traded anyway, though, the destination could have been better.

The Yankees of course play in one of the friendliest venues for hitters. Safeco Field isn't the pitchers park it was when it opened, but it's still a place that they're by and large happy to call home. For his career, Paxton has a 2.98 ERA there vs. 3.87 everywhere else, including 2.93 vs. 3.98 in just the past two years. Meanwhile, he has become more of a fly-ball pitcher in recent years and saw his career high for home runs in a season jump from nine to 23 this year.

Not a positive development considering where he's going.

James Paxton
BOS • SP • #65
2018 season
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But there's no second-guessing the decision from the Yankee's perspective. They're stuck with the park they're stuck with. It's a hurdle for any pitcher they'd bring over. It's less of one for a left-hander, who wouldn't be as vulnerable as a right-hander to the short porch in right field, and certainly less of one for a pitcher who misses bats like Paxton does. 

That is the part that shouldn't go unstated here. Though a late bloomer who didn't begin pitching up to his capabilities until late in 2016, Paxton's credentials aren't in question now. He's one of the hardest throwing left-handers in baseball, his fastball peaking at 100 mph, and there's depth to it, making it one of the best swing-and-miss pitches of its class. He has delivered the sort of strikeout-to-walk ratios we've grown accustomed to seeing from Noah Syndergaard, and with an arsenal that's not too dissimilar, frankly. Paxton isn't the 3.76 ERA pitcher he was for the Mariners in 2018. His 3.23 FIP this year and 2.98 ERA last year say more about his ability. And let's not forget he threw a 16-strikeout game and a no-hitter in back-to-back starts in May.

My hunch, then, is that he'll be fine and maybe even come out ahead with this deal. The biggest threat to his success is still his own body, which has so far prevented him from ever throwing 180 innings in a professional season (majors and minors included). But the venue change combined with batted-ball tendencies suggests there's a chance he dominates and again delivers a substandard ERA. A small price to pay for a favorable win-loss record? Probably, but I'm not eager to move him up the rankings considering.

That isn't a slight, mind you. He already checks in at 16th among starting pitchers.

Justus Sheffield
SEA • SP • #33
2018 minors
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As for the Mariners' big score in this deal, Sheffield will probably rate among the top 25-30 prospects in the game once preseason lists come out. He has a huge (some might even say Paxton-like) fastball, but suspect control and limited pitch variability may ultimately confine him to the bullpen. It doesn't help that his smallish size invites durability questions.

Still, anyone with that sort of stuff and pedigree has obvious sleeper appeal when he's knocking on the door to the majors. The Mariners are said to be especially high on him and will surely give him a chance to crack the opening day rotation, which is more than he would have gotten in Yankees camp. There's already enough odd men out there in Jonathan Loaisiga and Domingo German, who have both flashed greatness in limited big-league exposure.