The Seattle Mariners entered this winter with a robust agenda, and it’s now nearly complete.

Re-sign Josh Naylor: check. Find a lefty for the bullpen: check. Sign a right-handed platoon bat and come into spring training with a sufficient right-field depth chart? Check, thanks to Monday’s one-year contract for veteran outfielder Rob Refsnyder.

Between Refsnyder, Victor Robles, Dominic Canzone, and Luke Raley, the Mariners should be covered out in right. That leaves only one position on the diamond that needs an obvious upgrade: second base.

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Mariners should go full-throttle after Ketel Marte, Brendan Donovan

After losing Jorge Polanco to the New York Mets in free agency, the Mariners still have an opening at second base. Granted, third base remains open as well, but that seems more likely to be filled by a young infielder (namely, Ben Williamson, Cole Young, or Colt Emerson).

The Mariners should only be comfortable having one inexperienced infielder, and there are excellent trade candidates at second base. It’s time to make a strong push to trade for the Arizona Diamondbacks’ Ketel Marte (ideally) or the St. Louis Cardinals’ Brendan Donovan (perhaps more realistically).

With a legitimate case for the best farm system in Major League Baseball, the Mariners have no excuse to come up short to another team when it comes to offering the most for Marte. The only real holdup foreseeable would be ownership’s unwillingness to pay off his very affordable $102.5 million guarantee over the next five years.

If the Diamondbacks just aren’t willing to give up Marte unless a team grossly overpays, though, Donovan is a great fit. And since he’s under contract for just two more years, he could even give way to one of the younger infield prospects (Young or Emerson) in a couple of years.

Either way, the Mariners have no excuse to start the season with the lineup as it stands, and the second-base position is the only major upgrade that looks feasible.

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