So, good news on Marquez is that he's back on the mound. That's really the best news here. He's on the mound, and he's throwing. The velo reports are not what you'd love to hear; 101mph in the 5th inning just isn't there any more, and it's likely not coming back. Last go he was clocked in around 93-94mph. He's showing more of a 3/4rs/sidearm type of delivery than in the past which might help with some deception. There's probably a bit more velocity to clock in somwhere, as he gets his feet under him, but probably only a bit.
The one thing I'll say is this; the Cubs have had a knack of saving "dead" prospects here. Justin Steele, Miguel Amaya, and Adbert Alzolay were all, essentially, dead prospects and they're playing important roles on the roster right now. Cole Roederer is being resurrected at this moment as well in Tennessee. Brailyn Marquez can still be something. Maybe it's going to be a 7th inning arm instead of the 100mph flame throwing #2 in the rotation he looked like might have been in 2019, but hey, something is always better than nothing.
(and please, remember this when we think of Brennen Davis. He's not dead yet either).