He's entered with 13 runners on and allowed 5 to score (38%).
https://www.baseball-reference.com/players/gl.fcgi?id=lopezjo02&t=p&year=20254/9 - 7th inning, enters with 2 outs. 2 on / 0 score. 1.1 IP, 2 days rest, 0 runs allowed.
4/20 - 8th inning, 1 out. 2 on / 1 score. 0.2 IP, 3 days rest, 0 runs charged.
4/23 - 7th inning, 1 out. 3 on / 1 score. 1.2 IP, 2 days rest, 1 run charged. Blown save win
4/27 - 9th inning, 2 outs. 2 on / 0 score. 0.1 IP, 1 day rest, 0 runs allowed. Win.
5/6 - 7th inning, 1 out. 2 on / 2 score. 1.2 IP, 1 day rest, 1 run charged. Blown save win.
5/7 - 6th inning, 0 out, 1 on / 1 score. 0.0 IP, 0 days rest, 3 runs charged.
5/12 - 7th inning, 2 out, 1 on / 0 score. 0.1 IP, 4 days rest, 0 runs allowed.
He's been used 5 times with 0 days rest. As for the "fireman" mid-innings, guys on, he's allowed inherited runners to score 4 out of 7 times he's tried. He's gotten lucky with 2 blown save wins.
4/6, 1 IP (started the 8th), 2 hits, 1 run. hold
4/13, 1 IP (starts 7th), 3 hits, 3 runs (HR).
5/7 - see above. 3 hits and a BB
5/13 - 0.2 IP (starts the 8th), 2 hits, 1 HBP, 1 run.
5/16 - 1 IP (starts the 8th), 2 hits, 0 runs.
Pretty much can't be used on 0 days rest. Really dodged a bullet last night.
to me, it looks like he's best used with clean innings and at least 1 days' rest.