Milroe didn't just do poorly. he was the worst in FBS in holding the ball. Literally the worst - not my stat. That's PFF data.
I'm not sure what CTR could have done differently. Even when CTR adjusted by leveraging flood routes so JM only had to look at one side of the field, JM didn't execute the short throws that were WIDE open. It's hard for the OC to make an adjustment to take off the pressure when the QB is just so unable to be in sync with the flow of the play that he can't/won't pull the trigger to hit wide open routes to the point the D just backs off of them knowing there's almost no risk of JM completing that play. Really, what ability of JMs does CTR tailor to? Zone Reads? nope, JM couldn't read the end so had to take that out. Hot routes? nope - see above. Literally, what to do?