ROOKIES TO WATCH

Haniger and Ben Gamel will have plenty of eyes on them during spring training looking at whether they can be a capable outfield duo as part of a four- or five-man rotation that could be among the better defensive outfield units in baseball. While Haniger and Gamel are top prospects, both will need to show they can hit and bring more than just their defense.

Also watch out for what Tyler O’Neill does in spring training. Seattle’s top minor-league prospect is likely to begin the season in Triple-A, but a big spring could set the stage for an appearance in Seattle a bit earlier during the regular season than expected.

THEY’RE SET

Seattle’s infield and its starting rotation both appear set. Cano (second base), Segura (shortstop) and Seager (third base) are locks, with Daniel Vogelbach and Valencia splitting time at first base, and Mike Zunino and Carlos Ruiz splitting time behind the plate.

On the mound, Hernandez, Hisashi Iwakuma, James Paxton, Smyly and Gallardo — in some order — are the five Seattle wants to go into the season with. Still to be determined is whether Ariel Miranda goes to the bullpen or the minors.

THEY’RE NOT

Every spot in the bullpen — other than closer Edwin Diaz — is a bit of a question. The Mariners would like to see Marc Rzepczynski as their lefthanded specialist, with Nick Vincent, Dan Altavilla and Shae Simmons part of the group that gets the ball to Diaz. The few competitions during spring training will focus on the other couple of spots surrounding those.

ON DECK

Seattle will lose a handful of its stars to the World Baseball Classic for a chunk of March. That’ll give some of the younger prospects a chance to make an impression with the likes of Cano, Cruz and Hernandez away. When the WBC players return in late March, the Mariners believe they’ll be putting the finishing touches on a team ready to contend in the AL West.