The first major move of the 2018 MLB offseason was made on Monday night, as the Seattle Mariners sent James Paxton to the New York Yankees for Justus Sheffield, Erik Swanson, and Dom Thompson-Williams.

By trading Paxton, the Mariners got a top-50 prospect in the lefty Sheffield, a controllable arm in the righty Swanson, and an athletic player in Thompson-Williams, but the Yankees got a second legitimate flamethrower behind Luis Severino. Even though Paxton has never thrown more than 160 innings in a season, his performance over the last three seasons puts him among the top left-handed pitchers in the game.

With Paxton headed to the Bronx and a top prospect on the move to the Pacific Northwest, what is the impact of this trade on the Mariners and Yankees?

What Impact Will Paxton Have In Pinstripes?

With the World Series champion Red Sox possessing Chris Sale and David Price, the Astros with Justin Verlander and Gerrit Cole, and the Indians (for the time being) with Carlos Carrasco and Corey Kluber, the Yankees knew they needed to add another top arm. They did just that by adding the 30-year-old Canadian Paxton, who was 11-6 with a 3.76 ERA last season, striking out 208 batters in 160 1/3 innings. His FIP was also strong at 3.23 and this season was coming off of a 2016 season where his FIP was 2.80 and a 2017 season where his FIP was 2.61. Paxton also only allowed 134 hits last season (including a no-hitter in Toronto against the Blue Jays), seeing his WHIP fall to a career-best 1.10.

The most impressive trait for Paxton is his strikeout ability, as he was seventh in swinging strike rate among pitchers with 160 innings thrown in 2017 at 14.3%.  He also led baseball in swing percentage (52.4%) and allowed just 82.1% contact in the strike zone (8th in baseball). Paxton saw his ERA go from 2.98 in 2017 to 3.76 in 2018 (more on that in a moment), but his xFIP (3.02) was actually better than in 2017 (3.25). His K-BB% of 25.7 was fifth in baseball last season and he had two pitches that were top-15 value (fastball and cutter), as well as a plus pitch with his curveball. He has lost a tick on his fastball velocity, from 97.4 in 2016 to 95.9 this season, but it has continued to be one of the better ones in baseball. All told, since 2016, Paxton's 2.90 FIP is fifth in baseball, his 1.16 WHIP is 17th in baseball, and his 28.2% K rate is 11th in baseball.

An issue for Paxton is his fly ball rate, as he allowed a 41.1% fly ball rate last season (13th-worst of those that pitched at least 160 innings), up from 30.1% in 2016 and 32.7% in 2017. He also allowed a career-worst 34% hard hit ball rate and his ground ball rate was 39.6%, his worst ratio as a professional. The cherry on top was the fact that he allowed 23 home runs in 2018 after allowing 18 home runs in the two previous seasons. Yes, he allowed a career-low 72.6% contact rate, but he needs to do better at missing barrels when he does allow contact. On the positive side, though, both Justin Verlander and Max Scherzer did have worse fly ball ratios than Paxton. The worst thing about his batted ball trends, though, is that he will be moving from a pitcher's park in Seattle (27th in run factor) to a hitter's ballpark in New York (6th in run factor). There is also the fact that he allowed four runs in five innings in his only start in New York (June 21 of last season), allowing two homers in that game. While his fly ball rate was a bit better to close the season, he needs to watch his ratios now that he is in the Bronx.

Paxton's issue is his health, but, fortunately for the Yankees, he does not have a track record of shoulder or elbow injuries. His injuries have included a strained lat muscle, strained middle finger tendon, forearm strain or contusion and a back injury; none of these injuries were reoccurring either.  Also, while some may look at Paxton's lack of work due to injuries as a negative, this is still a 30-year-old that has not even pitched 600 big league innings. Signed through the 2020 season, look for Paxton to ink a long-term deal with the Yankees over the next two seasons and to flash SP2 potential with the Yankees. He will constantly be put in a good position for wins, but needs to monitor his fly ball rate in New York.

What Did The Mariners Get For Their Ace?

Any package from the Yankees was going to start with top prospect Sheffield, but it is surprising that the Mariners did not get any other players inside of the top-15 of the Yankees farm system. In fact, there are even questions on if Sheffield is even the ace that the Mariners could have been looking for. There were rumors that the Astros were close to a deal for Paxton, but were adamant that they would not trade Forrest Whitley.

With Sheffield, the Mariners are getting a 5'11 lefty with a stable of pitches that may match Paxton's; unfortunately, he isn't 6'4, 235 and also walked 12.5% of batters in Double-A and 9.9% in Triple-A. Command issues led to the Yankees delaying his promotion to the big leagues, no matter their starting pitching woes, and, when they did call him up, it was for just 2 2/3 innings as a reliever in September. His command issues continued in that small spell (three walks and four hits allowed), leading some to believe that he is an SP3 or high-end reliever rather than an ace in the future. He did also have a 2.48 ERA in 116 minor league innings, striking out 123 batters, so the potential is still there for him to be an impact player in 2019 and beyond.

As for Swanson and Thompson-Williams, there are things to like, but they are more lottery tickets than sure things. Swanson was acquired in the deal that sent Carlos Beltran to Texas in 2016 and he was 15-5 with a 3.24 ERA over the last two seasons spanning from High-A to Triple-A. In 2018, Swanson saw his strikeout numbers jump to 139 in 122 2/3 innings and his solid 4.07 K:BB rate in 357 minor league innings should lead to him being a part of the Mariners' rotation at some point in 2019 or early 2020 at the latest. Thompson-Williams was a 20/20 player in the low minors last season (22 home runs and 20 stolen bases between Low-A Charleston and High-A Tampa) and does have a .350 OBP in 897 plate appearances in the minors. At 24 in April, the Mariners will want to see if Thompson-Williams can handle a move up to Double-A to open the season and he could be a fourth OF in Seattle by 2021.

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