BALTIMORE -- There are only two teams in Major League Baseball that currently do not feature a southpaw in their bullpen. The ERA for one of those bullpens is 3.73, while the other is over a run higher at 5.00. One team has made itself a World Series contender, while the other has gone full-fledged rebuild. Hailing from the same division, they began Saturday separated by 28 1/2 games in the standings.

They are the Astros and the Mariners. And while Seattle holds four lefties in its rotation, the former holds just one on its entire 25-man roster -- and only three on the 40-man roster.

“I have to find some guys down there that can combat some of the left-handers,” Astros manager AJ Hinch said before Saturday’s game against the Orioles. “We’ll do it a little differently, but [the bullpen] being able to combat the left-handedness of another lineup is a great advantage for us.”

Take Friday’s 3-2 win over the Orioles as an example. With three lefties sitting on Baltimore’s bench, Hinch called on Will Harris to mop up a two-on, two-out situation in a one-run game. The Orioles could have countered with one of their lefties, but the righty Harris owns better splits against lefties (.514 OPS) than he does against righties (.693 OPS) this season.

Harris accomplished the job on Friday thanks to a caught-stealing. It also made for light-hearted clubhouse conversations on Saturday, regarding whether Harris should have gotten credit for completing one-third of an inning, which he did.

That allowed Joe Smith to come on for a fresh start in the sixth, and Ryan Pressley, who also owns better splits against lefties, made his first appearance off the injured list since July 26. Roberto Osuna came on to close it out. All done with just one lefty -- Friday’s starter Wade Miley -- against a lineup heavy on switch-hitters and left-handed batters.

Harris, in particular, has earned himself a more high-leverage role this season. Lefties own both a lower batting average and OPS against Harris this year than righties.

“I trust him as much as I trust anybody in my managerial career so far,” Hinch said of Harris. “He’s been really good for us over the last five years or so.”

Harris has earned that trust using his money-making cutter and curveball, two pitches that he throws a combined 98.8 percent of the time. He has a whiff rate of 27.8 percent, which is on the lower end for his career, but still far higher than the 24.2 percent Major League average. Opponents are barreling balls off him just 4.2 percent of the time, which falls within the top 8 percent of the league.

“The more that he throws a curveball for a strike, the more effective he is,” Hinch said. “You just don’t see that out of the bullpen as much anymore. … He’s got a unique arsenal and he’s got some deception. Hitters don’t take clean swings at him, and the better he does, the more that I continue to put challenges in front of him.”

But teams are still going to try and take advantage of the matchup when they can. Case in point, the Orioles stacked three lefties for Saturday’s game.

Even the looming reinforcements will not give Hinch any lefties at his disposal. Both Josh James, who is rehabbing from right shoulder soreness, and Brad Peacock, slated for a pair of rehab games with Triple-A Round Rock to close out the weekend, are righties.

But it’s no matter, because the Astros have made it this far without needing a southpaw. Yet with newly acquired Zack Greinke bolstering the rotation, it makes the potential movement of Miley and his 2.99 ERA to the 'pen all the more possible come October.

Rotation standing pat for now

Hinch added that the Astros do not plan to tinker with their rotation for the foreseeable future. So that means Greinke will make his second Astro start Monday against the White Sox, Gerrit Cole goes on Tuesday and Miley will go on Wednesday.