With a crowded rotation and beat-up bullpen, Red Sox pitching staff is coming to crossroads

Red Sox infielder Pablo Reyes came on to pitch the ninth inning on Monday.Jim Davis/Globe Staff

What does bottom look like? For the Red Sox, they hope that it’s the form the team took in the ninth inning of Monday’s game against the Mariners.

With the Sox being blown out by Seattle and their bullpen thinned by the injury-induced departure of John Schreiber, recently acquired utility infielder Pablo Reyes moved from shortstop to the mound. Reyes began his thankless task with a 34-mile-per-hour lob, ultimately allowing one run on two walks and two hits.

Somehow, his performance was the best of the night by a Red Sox pitcher in a 10-1 loss to Seattle.

“It sucks, man,” Red Sox manager Alex Cora lamented of his usage of Reyes, but said it had been necessitated by other relievers being “banged up” and limited in availability. “That’s the worst feeling as a manager.”

Presumably, Reyes won’t soon return to the mound, but his brief cameo underscored that the Red Sox pitching staff is amidst a shakeup — partly by design, partly by necessity.

On one hand, the impressive return of lefthander James Paxton last Friday, bookended by outstanding outings from Brayan Bello last Wednesday and Chris Sale on Saturday, offered a glimpse of a potential anchors for the team’s competitive aspirations.

Yet almost everything surrounding those three has fallen apart. The Sox have allowed 31 runs over their current four-game losing streak (7.8 per contest), and 48 while going 1-6 over their last seven games (6.9 per game).

In the last week, starters Nick Pivetta and Corey Kluber have been shelled. On Monday against the Mariners, Tanner Houck continued his pattern of excelling early in games — he raced through three perfect innings and retired the first 11 batters he faced — before going off the rails when navigating an opposing lineup for the second time.

After a strong start Monday, Tanner Houck's second spin through the lineup was a struggle.Jim Davis/Globe Staff

He allowed four runs on five hits and a walk to the last 10 batters he faced. In 28 career starts, Houck has held hitters to a .164/.248/.205 line the first time through a lineup, while getting blasted at a .288/.352/.447 clip thereafter.

“If I had an answer [for the struggles after the first time through the order], I think we wouldn’t be talking about it,” said Houck. “It’s an ongoing conversation.”

It’s one of many, as the Sox try to patch their pitching staff.

The loss of multi-innings reliever Kutter Crawford to the injured list with a hamstring strain has left a gaping hole in the bullpen. While Crawford is nearing a return — he’s slated to throw for Triple A Worcester on Tuesday, then be activated in San Diego on Friday — Schreiber is expected to be placed on the injured list Tuesday with a lat injury that forced him from Monday’s game. The back-to-back meltdowns of Kenley Jansen on Friday and Saturday offered unexpected amplification to the team’s pitching woes and muted the feel-good performances of Paxton and Sale.

Ryan Brasier was designated for assignment to clear a roster spot for lefthander Joely Rodriguez. Lefthander Brennan Bernardino was optioned to Worcester after Monday’s game so the Sox can add multiple WooSox pitchers Tuesday while trying to protect a staff that seems thin.

For much of the early season, the Red Sox have remained competitive in spite of subpar pitching, thanks to an offense that has forgiven many mound sins. But the ability to do so has limits, particularly now that opposing pitchers (including Mariners starter George Kirby in a brilliant 6⅔ inning, one-run effort Monday) have proven capable of quieting the lineup.

Put simply, the Red Sox’ pitching hasn’t been good enough. The staff has a 5.09 ERA, a mark that is fifth worst in baseball, ahead of the rebuilding Reds, Royals, and A’s, and the desperately disappointing White Sox. The rotation (5.82 ERA, third worst in MLB) has been particularly abysmal.

George Kirby gets a nice hand from the Seattle fans at Fenway Monday night after his night was complete.Jim Davis/Globe Staff

There are reasons to believe that improvement is within reach, starting with Sale, Bello, and Paxton. It’s possible the team can reassess Houck’s role — in light of his uneven performances as a starter and Schreiber’s injury, though Cora did note the pending return of Crawford decreases the pressure to shift Houck out of the six-man rotation.

The return of Crawford (3.51 ERA, 24 strikeouts, 3 walks in 25⅓ innings) to the bullpen this week and Garrett Whitlock perhaps by the end of next week from the injured list will permit a staff reconfiguration. There are possibilities for a course alteration.

With that in mind, the Sox are trying to take a broader view and avoid overreacting to recent struggles — both by individual pitchers and the team.

“Sometimes we get drowned in [a] glass of water from one outing or one weekend talking about stuff that really doesn’t matter in the sense [that] it was [just] a bad weekend,” said Cora.

Yet the glass is getting bigger, and for the first time since they suffered a four-game sweep at the hands of the Rays in early April, the Red Sox appear to be flailing to keep their heads above water.