CLEVELAND -- While the rain fell Tuesday night at Progressive Field, Ryan Carpenter spent most of the two-hour delay in the Tigers dugout. There was no chance of him going back into the game, either due to the duration of the rain or the downpour of offense the Indians compiled against him for an 8-0 Detroit defeat. Instead, Carpenter was left to ponder.

“That’s just the nature of where we’re at right now,” Tigers manager Ron Gardenhire said. “He’s facing a good-hitting team over here that can do some things. Every mistake he made, it seemed like they got a hold of it pretty good.”

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Meanwhile, Gardenhire was back in his office in the clubhouse, likely pondering the same question the Tigers front office has had to consider for the last couple weeks: Who among their pitching prospects can fill the back end of their starting rotation? And how soon can they be ready?

The fact that Carpenter was recalled from Triple-A Toledo on Tuesday for this start was a reflection of the organizational belief that the answer isn’t “now.” Cleveland’s seven runs over the first three innings raised Carpenter’s ERA from 8.36 to 9.30. The Tigers are 2-7 in his starts, though his seven quality innings in a June 4 victory over the Rays made him the only Tigers starter to earn a win last month.

Detroit has lost Carpenter’s last four starts since then by a combined 42-12 margin. Once Oscar Mercado followed Francisco Lindor's two-run double with a two-run homer to push Cleveland’s lead to 5-0 in the second inning, Tuesday’s outcome wasn’t in much doubt, nor was the postgame move sending Carpenter back to Toledo.

“He’s gotta go back down, he’s gotta go compete again,” Gardenhire said. “Because this is going to probably happen again.”

Unlike most of the season’s first half, the Tigers can’t go with a four-man rotation. There simply aren’t enough off-days to skip the spot and let Matthew Boyd, Daniel Norris, Spencer Turnbull and Jordan Zimmermann start on regular rest. Detroit is in the midst of a stretch of 19 games in 20 days, then will play 24 games over a 25-day stretch in August.

“When you start to play all these games in a row, it makes a difference,” Gardenhire said.

The Tigers will need a fifth starter no later than Sunday at home against the Blue Jays. Barring an injury, it won’t be Carpenter, who won’t be eligible to return by then.

General manager Al Avila suggested earlier this month that the Tigers could use the fifth rotation spot to evaluate a few prospects down the stretch. Since then, Kyle Funkhouser's struggles have led to him taking a step back from Triple-A Toledo to Double-A Erie to work out mechanical issues.

So, who could be ready? A look at the potential candidates:

• LHP Tyler Alexander: The former second-round pick out of TCU made a spot start in a July 3 doubleheader against the White Sox and delivered five innings with four strikeouts, his only damage coming on two solo homers. His stuff isn’t overpowering, but his funky delivery and movement present a different look to hitters. The 25-year-old is in line to start for Triple-A Toledo on Friday, but could easily be held back to return to Detroit for Sunday. “He’s off to a great start,” Avila said of Alexander a week and a half ago.

• RHP Beau Burrows: Avila has said publicly that Burrows is in line for a chance if the former first-round Draft pick does what the Tigers expect this summer. His five innings of one-run ball Monday for the Mud Hens presented a big step in the right direction. He has a 1.50 ERA in four starts since his return to Toledo from shoulder inflammation. Though Burrows isn’t on the 40-man roster, the Tigers have to add him at year’s end anyway to protect him from the Rule 5 Draft.

• RHP Kyle Funkhouser: Though a return to Erie is not a good sign at midseason, the Tigers could still find a spot for him if he can figure out his issues and pitch his way back into the mix. He looked like he was on the verge of the Majors after six scoreless innings against Louisville on June 26, but gave up 17 runs on 23 hits over just 8 2/3 innings in three starts since, including a seven-run, five-out performance with Avila in attendance July 1.

• LHP Gregory Soto: Though many in the organization see Soto’s future as a hard-throwing reliever, team officials want him stretched out as a starter for use down the stretch. He gave up an earned run over three innings with five strikeouts for the Mud Hens on Tuesday, but like Carpenter, he won’t be eligible to be called up for Sunday since he was optioned last weekend.

• RHP Drew VerHagen: Though the Tigers outrighted VerHagen off their 40-man roster earlier this season after a miserable stretch in the bullpen, he has found his better form as a starter in Toledo, posting a 4-2 record and 4.82 ERA in 10 starts while striking out 44 batters over 46 ⅔ innings. His stock took a drop after giving up eight runs over 1 2/3 innings to Triple-A Louisville last Saturday.

Two who aren’t likely to get a chance this season are top prospects Casey Mize and Matt Manning (Nos. 1 and 2 in the Tigers' system, respectively, according to MLB Pipeline), neither of whom has to be added to the 40-man roster this year. Neither has pitched in Toledo yet, which the Tigers see as a key step in development. Mize’s stint on the injured list with shoulder fatigue slowed his progress a bit regardless, while Manning’s domination of Double-A hitters has been tempered of late.

Though the Tigers have seen the excitement other clubs have received when top prospects have arrived, Avila doesn’t want to rush the process.