M’s outfield will be faster, more athletic with offseason additions

General manager Jerry Dipoto’s offseason roster makeover produced two major additions to the Mariners’ outfield — Leonys Martin, acquired in a trade with Texas, and Nori Aoki, who signed with Seattle as a free agent.

The two newcomers address the goal of fielding an outfield possessing the requisite athleticism, speed and range to tame Safeco Field’s spacious dimensions. Putting Martin in center field should aid every pitcher on the staff.

Gone are the days of enduring Mark Trumbo (dealt to Baltimore) labor in the outfield corners or watching shortstop Brad Miller and second baseman Rickie Weeks undergo on-the-job training as outfielders.

Martin will be in center field and Aoki is ticketed for left, which means last season’s left/right platoon of Seth Smith and Franklin Gutierrez will shift corners to right field.

That seems to position Nelson Cruz as the primary designated hitter, although he’ll likely play right on occasion — say, when Martin or Aoki gets a day off.

Who’s in camp?

Nori Aoki (Bats left, throws right, 5-feet-9, 180 pounds, age 34 on opening day): A Dec. 3 free-agent signing who fills multiple needs. He projects as the leadoff hitter because of consistent on-base skills and should add speed and defense as the primary left fielder.

Nelson Cruz (R-R, 6-2, 230, 35): Likely to see increased time this season as the designated hitter to keep him fresh. Even if he regresses a bit from what might have been his best career year, Cruz remains a potent force in the middle of the lineup.

Franklin Gutierrez (R-R, 6-2, 200, 33): His ongoing spinal and joint issues still require monitoring, but he proved last year that he can provide punch in a part-time role. Should share right field with Seth Smith.

Leonys Martin (L-R, 6-2, 200, 28): A trade acquisition from Texas who should solve the Mariners’ high-priority need for a strong defensive center fielder even if he has another disappointing offensive season. If his bat bounces back, he could make a major impact.

Boog Powell (L-L, 5-10, 185, 23): Acquired in November from Tampa Bay, he’s likely ticketed for Triple-A Tacoma. But the Mariners love his speed and on-base skills. Could get mid-to-late season promotion.

Stefen Romero (R-R, 6-2, 220, 27): His time in the organization is probably running out, and there’s again no clear spot for him. But he’s flashed potential in the minors, which makes him tough to give up on.

Seth Smith (L-L, 6-3, 210, 33): He remains a solid and steady (if unspectacular) left-handed bat. Smith will collect 30 doubles and a dozen homers while batting .250-.260. Provides good pairing with Gutierrez in right field.

Non-roster invitees

Mike Baxter (L-R, 6-0, 205, 32): Almost certain to start at Triple-A Tacoma, but he’s the sort of proven player that clubs love having in their system. In a pinch, he can come to the big leagues and provide a professional presence.

Dan Robertson (R-R, 5-8, 205, 30): He has a different skill set than Mike Baxter, but he’s also a reliable veteran who figures to log time at Tacoma until-and-if needed in the big leagues. Batted .274 with a .324 OBP in 107 games for the Angels over the past two years.

Dario Pizzano (L-R, 5-11, 200, 24): Another example of the Mariners’ new effort to re-enforce the desire for high on-base skills. His invite over some higher-profile prospects can likely be traced to a .383 OBP over four pro seasons.

Three things to watch

1. Aoki ended last season on the disabled list because of lingering concussion issues. He says he’s fine, and he got a clean medical report before the Mariners finalized his contract. But he needs to prove he’s fine on the field.

2. Gutierrez proved capable last season of managing his ongoing health issues while simultaneously resurrecting his career. But there’s no guarantee his symptoms won’t escalate and derail him. It’s a sad truth that he lives with.

3. Martin showed improved plate discipline in winter ball. Can that trend continue?

Spring forecast

The Mariners figure to keep five outfielders, counting Cruz, and barring injuries, all five spots are set. But four of those five players will be 33 or older on opening day. So injuries are an increasing possibility.

That makes it an important camp for everyone else. Powell, in particular, figures to get a long look because he’s viewed as a legitimate starting candidate at some point in the near future. The job for Romero, Baxter, Robertson and even Pizzano is to position themselves at the top of the pecking order in case the Mariners need to dip into their farm system for help.