Pro days are part of the evaluation process NFL clubs use in the run-up to the NFL draft. However, two evaluators can watch the same pro-day performance and have two very different takes on it. It's a highly subjective exercise.
Some pro days are used to confirm what scouts have seen on tape. Other showings have sent those same scouts scrambling to re-check something they might have missed. There are some poor pro-day outings that could lead a team to drop a prospect way down on the draft board, if not off of it.
The vast majority of players leave a positive impression on teams thanks to scripted workouts. For the handful of others that don't, though, they might be seeing a Teddy Bridgewater-like slide after failing to meet expectations. Bridgewater, the former Louisville quarterback, went from potential top-five pick to the last pick of the first round (No. 32 to the Vikings) last year, becoming the poster boy for sliding draft expectations in the wake of a bad pro day. He might be joined, though, by some of the players on this list, as they saw their stock drop after iffy, at best, pro-day workouts this draft season.
Big 12 observers would tell you Bibbs was one of the few bright spots for Cyclones the past few years. Although a little smaller than some would like, he displayed a knack for catching and running, and even could move to fullback in the NFL based on his skill set. He had just an average pro-day workout, though, and ran slowly with a 4.86 in the 40-yard dash. It's a weak tight end class, but NFL Media senior analyst Gil Brandt views Bibbs as a likely undrafted free agent after the workout.
Daniels served a suspension for academic dishonesty during the 2014 season, so there was plenty of interest in how he would fare at the Irish's pro day. Although he looked pretty athletic, his speed wasn't all that impressive (he ran in the 4.5 range in the 40) and he didn't look real sharp during drills. Given the depth of the class at receiver, such a workout sent his stock in the wrong direction.
The safety class this year is extremely weak outside of Alabama's Landon Collins, so Harris could have used his pro day to vault himself higher in the minds of scouts. However, Harris didn't work out with other UVA players at the pro day. He's recovering from shoulder surgery and is missing opportunities to boost his stock, as he also was unable to work out at the NFL Scouting Combine.
Perryman has been hit by the injury bug, which limited him at the combine and at his pro day. Being hindered in those opportunities was a big blow for Perryman, as scouts want to get a better feel for his athletic ability. His tape is great, but questions still linger about him.
Penn State players
After not being cleared to run at the combine due to a to injury, Ray posted slower than expected times in the shuttle and 40-yard dash at the Missouri pro day. He showed a lack of flexibility and had some issues in coverage during linebacker drills, so it wasn't hard to see why Ray's stock took a hit. NFL Media analyst Mike Mayock was in attendance for the workout and wasn't impressed. In fact, this week he dropped Ray in his positional rankings from second to fifth among edge rushers.
Oregon's Marcus Mariota didn't have a great pro day, but his stock seemed to stay level afterward. Winston also didn't perform at the high level we're used to seeing from him during FSU's pro day, but the signal-caller has seen his stock take at least a small hit following the workout. The pro-day showing probably isn't enough to make the Tampa Bay Buccaneers' decision makers change their minds about whether he's worthy of the No. 1 overall pick, but it's worth noting that Mayock moved Winston from first to second at quarterback in the positional rankings he released this week.