BALTIMORE –– The Red Sox are quickly learning Jon Lester is the guy to have on the mound to halt a losing skid.

Sure, Boston had lost only two straight before Lester led the club to a 6-3 victory over the Orioles last night, but his numbers after a loss this season are impressive.

The left-hander, who improved to 12-4 on the season, is 5-1 with a 1.41 ERA in nine starts after a Red Sox loss. Also, he’s 5-0 with a 1.01 in his last six outings, following a loss.

“I didn’t know that,” he admitted. “That’s something you don’t pay attention to. You want to go out every five days and give quality starts, whether we’ve won or lost the game before. It doesn’t really matter because you want to go out and just pitch your game and hopefully we come out winning.”

There’s no doubt Lester has become an ace and he continues to prove that every time out. The A.L. Pitcher of the Month for July (3-0, 2.05 ERA in four starts) is off to a 3-1 start this month and shows no signs of letting up.

“I don’t think my mindset has changed since April,” Lester said. “I’m more consistent and I’m pounding the zone with strike one. When you can prove to guys that you’re around the zone and able to get ahead of them, they’re going to swing at pitches early in the count that aren’t necessarily good pitches for them to hit. I was able to do that tonight.”

While Lester kept the Orioles at bay last night, teammate Jason Bay did his part to help the southpaw earn his 12 win of the season. Bay, who drilled a pair of home runs and drove in a total of four runs, has been impressed with Lester since his arrival late last month.

“He’s one of the better pitchers in the league,” Bay said. “Every start he’s had since I’ve been here he’s been good, even the start his lost in Chicago. I’ll be honest, I didn’t know a lot about him before I got here, but it’s pretty obvious to me now he’s one of the better pitchers in this league.”

Even Lester’s original teammates knew exactly what kind of pitcher he would become.

“Everybody knew Lester was going to be at that level,” said David Ortiz. “The way he pitches and the stuff that he has will make his a superstar at this level.”

jmcdonal@projo.com