CINCINNATI — The Phillies’ bullpen has sustained another injury.

On Thursday, the club announced that left-hander Tanner Banks was heading to the injured list with a strained left forearm.

It’s their ninth reliever IL stint, if you include Orion Kerkering’s hamstring strain, which he entered the season with. Overall, it’s been a bullpen that has gone through rough patches and stretches of fatigue.

As a group, Phillies relievers have produced the sixth-highest opponents’ average at .255, the third-highest mark in the National League. More specifically, it’s been their southpaws who have experienced the most ineffectiveness. The club’s lefties have allowed the highest opponents’ OPS at .831.

Banks, who allowed four runs and got just one out in Wednesday’s contest, has produced a 7.14 ERA. José Alvarado, who also allowed four runs a night ago, inflated his ERA to 7.03.

Banks had been dealing with something before the IL move, though the severity remained unclear to Don Mattingly.

“I heard a little bit about it, but it didn’t sound like it was much of anything,” Mattingly said. “It sounds like he was OK during the game, but he was having trouble getting moving and getting it going every day.”

That was enough for the Phillies to investigate further.

“That kind of told us something’s going on, and obviously it’s affecting maybe a little bit how the ball’s coming out,” Mattingly said. “So I feel like it was time to find out what’s going on.”

Mattingly said he had heard about the issue when Banks was in Triple-A, when it was described as forearm fatigue. Banks continued to say he was good to throw, but the Phillies sent him for testing after Wednesday’s outing.

Maybe that explains some of what has gone wrong.

“That’s a possibility,” Mattingly said. “That this is what’s been causing some of the lack of command and things like that.”

Either way, it further highlights one of the true blemishes on the roster.

While Jhoan Duran has been terrific as ever, the club needs relievers who can bridge to the ninth inning. For the three previous seasons, the Phillies had lefty Matt Strahm, whom they traded to Kansas City for Jonathan Bowlan in the offseason. The tall lefty produced a 2.71 ERA in 188 outings in that span.

Philadelphia is not missing much, though. Strahm, who is making $7.5 million in his final year of arbitration, has a 5.40 ERA, allowing eight homers in 30 innings.

And after picking up Alvarado’s $10 million club option, adding lefty Kyle Backhus, who has also struggled, and breaking camp with Tim Mayza, who owns a 2.81 ERA in 2026, there was a sense they had enough left-handers to get lefty batters out and hold their own against righties.

Brad Keller, who signed a two-year, $22 million contract, can get lefties out, too, when he is at his best, as he was in 2025.

That has not been a formidable group in 2026.

Mattingly acknowledged Wednesday night that the Phillies may have to think less about traditional matchups and more about who is throwing the ball best.

“I think we have to look at that,” Mattingly said. “Not necessarily trying to match up. Just going with the best guy right there.”

Dave Dombrowski, Preston Mattingly and the rest of the Phillies’ front office will have to bring in a left-hander who has some leverage value.

Boston’s Aroldis Chapman is the biggest name who could be available at the Aug. 3 trade deadline. He’ll also likely carry the heftiest price tag of any reliever swapped.

Chapman has tallied 18 saves thus far in his 17th big-league campaign. His average fastball velocity is still at 97.5 mph. Coming off a season in which he posted a 1.17 ERA, he has registered a 2.36 ERA in 28 appearances.

Now, a big question could be this: Can he set up Duran?

Before getting to Boston and filling its closer duties last season, Chapman worked in a setup-type role in 2023 with Kansas City and Texas, where he won his second World Series, as well as 2024 with Pittsburgh.

So the answer is yes.

And that would be a lethal velocity duo with the right-handed Duran. It would also give the Phillies another arm who could close games if called upon.

If the Phillies are unable to acquire Chapman, they will have to get creative.

There are a number of lefty reliever rentals, in other words, on expiring deals. New York’s A.J. Minter (0.53 ERA in 17 games) and Brooks Raley (2.16 ERA in 37 games) are of that variety, but both make some money, especially Minter, that could tack onto the Phillies’ luxury tax fees.

Cincinnati’s Caleb Ferguson and Colorado’s Brennan Bernardino are also options.

But if you look beyond this year, there is not a whole lot of light at the end of the tunnel when it comes to left-handers in the bullpen. The organization does not have a clear-cut name it can pull up from the minor league system, so acquiring one with some team control would be wise.

Why not call up Kansas City’s J.J. Picollo again?

Not for Strahm. For Daniel Lynch IV.

The 29-year-old, who is arbitration eligible for two more seasons after this one, is having a breakout campaign, posting a 2.41 ERA in 38 games. The former big prospect moved into the Royals’ bullpen three seasons ago and has gotten better and better.

This year, he’s filling up the strike zone, missing barrels and has found himself completely.

The two pitches, out of the five in his repertoire, that have powered the breakout are the slider and his main pitch, the sinker. His slider this season has experienced nearly a 15 percent increase in swing-and-miss rate to 44.2 percent. Opponents are batting .158 against the delivery with a .289 slugging percentage.

His sinker, which he’s throwing 10 percent more this year, has become his most-used pitch. It has strong life, has bumped up in velocity and has held opponents to a .125 average.

It’s exactly the kind of pitcher the Phillies could be looking for if they’re trying to find their old version of Strahm. Like Strahm, Lynch came up through the minors as a starter and has given the Royals some length in the past when needed. But this year, he has slid into a higher-leverage role with the rest of their bullpen struggling.

We’re still 25 days from the trade deadline, but Philadelphia has a clear need in its pitching staff.

Reinforcements should be on the way.