The organisation used a valuable and limited resource to bring Concepcion in when it is quite possible he won't even be there when they are on the clock. A top 30 is many things, but meaningless is not one of them. So why bring him in?
Injury checks? He had a 'routine' knee scope last month, knee arthroscopies on 21 year olds are not routine, there is a reason, so seems sensible to check that out.
Interviews? He has no character concerns, but has had a journey with a childhood speech impediment. He did a few interviews at the combine that show it and are worth viewing, and he advocates for others with similar issues. I can 100% see why a team would want to bring him in to the team facilities and get to know him a bit better and see the fit.
Private work out? He did all the drills at the combine, but none of the testing, and only ran the 40 at his proday, and as you say drops, speed variances on routes etc, there are a few issue so quite possibly.
Film work? Can he fit into McDaniels offense. He is supposed to have a good football IQ, a chance to test it.
Setting the board? Definitely. If he drops and all the OTs and Mesidor etc are gone and you can't trade down where does he fit?
I think this top 30 is actually quite an interesting one for all the reasons above. Maye needs someone who can get instant separation. He may be on their board for 31, maybe lower, maybe off it as you say. I like the guy and would be happy if the Pats drafted him at 31, although there are other players I would prefer.