Haggerty, summoned earlier in the day from the Mariners' alternate training site in Tacoma, started in left field during Wednesday's win over the Dodgers and went 1-for-4 with two strikeouts.
The 26-year-old began his second major-league tour of duty with Wednesday's start after having logged four plate appearances over 11 games with the Mets last season. Haggerty showed well as a hitter in both spring training and summer camp, but a hip injury during the latter short-circuited his chances of making the Opening Day roster. Haggerty notably slashed .310/.383/.524 at Triple-A Syracuse before his promotion last season, so he brings some offensive upside to the table and has experience playing every non-pitching position except catcher and first base.