I don't think how he did in the receiving drills will make much difference overall. Whoever drafts him - and I think he will be drafted - knows that Waller has some work to do on short routes; we don't throw them much. Oth, I think any NFL scout would look at him and see that this probably won't continue as a problem, what ever position he ends up in.
I also wasn't surprised by his 40 times. Coach always said he had the physical tools and anyone can look at the game films and see that he has a good turn of speed, especially for his size. Now it's up to the coaches.