DETROIT — When the Tigers made a six-player deal with the Seattle Mariners at the trade deadline in 2011, acquiring the piece in starter Doug Fister that helped cement their first-ever American League Central title, there was one trade chip experts said they’d probably regret giving up.

That was minor-league third baseman Francisco Martinez.

On Sunday, the Tigers made another deal with the Mariners to bring Martinez back to his original organization, swapping a player-to-be-named-later or cash for the 22-year-old. The swap will be completed within two weeks.

Martinez had been the No. 4-rated prospect in the Tigers system at the time of the 2011 trade, according to Baseball America, but never progressed past Double-A in the Mariners system, and was hitting .206 with no home runs and five RBI in 34 games at Jackson this season.

To make room for Martinez on the 40-man roster, the Tigers designated for assignment last year’s role player hero Quintin Berry, who’d been hitting .168 in 49 games with the Triple-A Toledo Mud Hens, where he'd been languishing since being one of the final cuts in spring training.

Detroit now has 10 days to either trade, release or place Berry on waivers. That’s essentially the process that made Martinez available for the Tigers. He’d been designated for assignment amidst a flurry of moves on May 27, and the Mariners worked out a deal to send him to Detroit, rather than keep him.

Regardless of whether the Tigers send a player or cash to the Mariners, the original deal looks more and more lopsided by the day.

Of the six principals in the 2011 trade, only two — Doug Fister and Charlie Furbush — are currently with the big-league clubs in either organization.

“You don’t make trades that don’t help both sides,” Tigers GM Dave Dombrowski said at the time. “We gave up a lot, we knew we gave up a lot, but that was the cost of acquisition of a starting pitcher, and players, really. You can see what some of the players that are getting traded at this point, what’s being involved in moving them.”

Furbush has appeared in 82 games as a reliever for the Mariners over the last two-plus seasons, posting an 8-12 record and a 4.56 ERA.

Casper Wells has been DFA’ed by the Mariners, Blue Jays and Athletics already this season, and is currently hitting .158 in 11 games with the Chicago White Sox.

Tabbed as potential closer material, Chance Ruffin struggled at Triple-A Tacoma for the Mariners, and was sent down to Double-A Jackson to make the transition into a starter this season.

“In this deal, what we did is we acquired players that we're going to have for a long time,” Zduriencik told the Seattle Times in 2011. “When you start looking at controlling younger players for five or six years, that's pretty good. That’s something that we said; we wanted to accumulate talent and try to stockpile players who will be here for a long time, players that fit needs that we have.”

That didn’t work so well.

On the Tigers side of the deal, reliever David Pauley appeared in just 14 games before the Tigers DFA’ed him. He spent five games each with the Angels and Blue Jays in 2012, then was signed to a minor-league contract to rejoin the Mariners organization, but was suspended 50 games for a violation of the MLB drug policy.

Fister, of course, has started 48 games for the Tigers, amassing a 23-13 record — including 8-1 down the stretch after the trade — with a 3.02 ERA.