I think taking a chance on a guy like Isabella in the 4th or 5th round is okay even though you should not expect him to a full time receiver. I am all in on Deadpool's positional bias of 6 feet for a WR but Isabella isn't anywhere close and his catch radius is Austin like. Austin was one of those terrible mistakes by Fisher/Snead. A small WR who wasn't a good route runner, had small hands, small catch radius but was fast as they come. Maybe the Robinson pick was worst but Austin is a close 2nd.
Anyway taking a gadget guy in round 4 and putting a package of plays for him where he can make an impact right away provided he can win a returner job on special teams makes a lot of sense. The guy would be active since he won the returners job and you get to use him as a surprise weapon with a limited package designed to get him the ball in space. I am not saying Isabella is that guy but a returner who can come in an contribute on offense would be nice. Currently Jo Jo Natson takes up a roster spot with no ability to play offense.