MLB 2017: One X-factor for each team

 Seattle Mariners: SP Felix Hernandez

Some chinks showed up in King Felix’s armor last season, with a strained right calf dropping him below 30 starts for the first time in his career (over a full season) with a drop-off in peripheral indicators and a 3.82 ERA. Gradual signs of decline have shown in recent years, and having pitched over 2,400 innings in his career has surely diminished Hernandez from his peak years.

But Hernandez is still the ace of Mariners’ pitching staff until further notice, and manager Scott Servais named him the Opening Day starter all the way back in January. Mariners’ general manager Jerry Dipoto had an incredibly active offseason on the trade front, too much so by many estimations, but pitching acquisitions Yovani Gallardo and Drew Smyly are simply starting rotation filler behind Hernandez, Hisashi Iwakuma and breakout candidate James Paxton.

After a 86-76 season in 2016, the Mariners may be primed to take the next step toward a playoff spot or even a division title this year. A remodeled roster looks fairly good on the surface, and perhaps most importantly depth shouldn’t be an issue. But Hernandez’s performance will tilt things one way or the other for the Mariners in 2017, and another injury-shortened campaign can’t be ruled out.