James Paxton: $9.0 Million – DEAL

This one is incredibly easy. Paxton had arguably his best season to date with the Mariners. Yes, his E.R.A was higher than in 2017. He did show more durability this year, pitching a career-high 160.1 innings, besting his previous best by 24.1. This is a huge improvement for someone who needs to show that innings eating ability to be considered an ace.
Getting his innings up was the main question surrounding Paxton. If the Mariners can get a mix of the stuff that he brought in 2017, and the innings in 2018, they have a bonafide ace. He has shown a little bit of all the things that it takes to be an ace. Now he just needs to put it all together.
Paxton at nine million is still a great deal, as he would get at least twice that on the open market. Heading into his age 30 season, the fact that the Seattle Mariners have their ace at well below market value is a nice bit of savings. As the most important Mariners arbitration candidate, Seattle will definitely say DEAL to James Paxton.