1375477729_2021500591Robby Thompson is serving as acting manager of the Seattle Mariners while Eric Wedge recovers from a mild stroke, and the interim chief has been doing so well that Cincinnati Reds skipper Dusty Baker believes he is ready for a more permanent managerial position.

Baker might want to rethink that claim.

In Thursday’s game against the Red Sox, Thompson and the Mariners held a five-run lead in the bottom half of the ninth inning before pitcher Tom Wilhelmsen allowed four consecutive batters to reach base without recording an out. With switch hitter Shane Victorino up and righty Dustin Pedroia on deck, Thompson headed to the mound to bring in right-hander Yoervis Medina from the bullpen.

However, Medina was warming up next to lefty Oliver Perez,  and when Thompson made the signal to the pen, he mistakenly threw up his left arm, indicating he wanted the southpaw. Thompson quickly realized he had made a mistake and tried to signal for Medina, but it was too late.

“I did point to the pen, but I didn’t have time to [tap his other arm] for the right-hander,” Thompson told MLB.com.  “He’d already turned. That’s when I wanted to make sure he knew who I wanted to go to and [crew chief] Gary Darling said it’s too late, you raised your left hand up.

“We wanted to go to Medina there and if we had to go to Ollie, he was the next guy. If there was anything today for me, it was a lesson learned that if you make a motion with either hand, that’s it. I didn’t realize that.”

Perez entered the game and allowed singles to Victorino and Pedroia before striking out David Ortiz. Medina finally entered the game with one out, but the damage had already been done as the tying run was on second base and the winning run was on first.

Jonny Gomes knocked in Victorino with an RBI single, Stephen Drew walked, and Daniel Nava sent the crowd home happy with a walk-off RBI single, giving the Sox back-to-back walk-off wins.

In theory, major league relief pitchers should be able to put out hitters from both sides of the plate, considering that is what they get paid millions to do. However, it is common baseball knowledge that right-handed pitchers typically have more success against right-handed batters, and left-handers are more effective against lefty batters. So while the dramatic loss shouldn’t be placed entirely on Thompson’s shoulders, his mistake definitely put the odds in the Red Sox’ favor. It’s safe to say Thompson learned this lesson the hard way.