The last time through the rotation, SWR, Festa and Matthews combined for 10 innings, 7 runs and 28 baserunners. That's a 6.30 ERA and a WHIP of 2.8. The previous time through they had 13.1 innings, 10 runs and 23 baserunners. That's a 6.75 ERA and a 1.77 WHIP. Combine those and you've got 23.1 innings (less than four per start), 17 runs (6.56 ERA) and 51 baserunners (2.19 WHIP).
They are likely key parts of the future, but in late-September 2024, they seem gassed.
In his four outings since being recalled, Irvin has pitched 12.2 innings, with 7 runs (4.97 ERA) and 18 baserunners (1.42 WHIP), It looks like there's a reason he was on waivers, but even with that, he's still pitched better than the rookies recently.
He may or may not be part of the future,* but for late-September 2024, it seems like a prudent move.
*See Seth's note above. I think he's not a bad flyer for the future in comparison to some non-tender candidates currently on the pitching staff, but for now, it's more about these two weeks.