It is not hard to see how Praise Martin-Oguike is both a good player, and an undrafted one.
If you want to know if he's a good player just look at any video of Temple's defense, find defensive end #50 (he also plays on the inside on some downs, or from an up position), and just WATCH him. That's all. Here are a few:
https://youtu.be/n-XQI1ygSBs
https://youtu.be/AtrN78cmDyM
https://youtu.be/VJCGmq8X-wg
I don't need PFF to tell me the guy plays with perfect leverage, has incredible upper body strength pound for pound, pretty much NEVER looks completely blocked, is always tracking the ball and easily sheds blockers to get to it, and also has a nasty habit of beating offensive linemen in pass rush, and nobody in college has forced more fumbles (11) over the last three seasons. It's nice for PFF's statistics (as opposed to the ratings) to give you some confirmation that these things happen in games that you've not watched, but it's clear he's a good player. He looks and plays like James Harrison and/or Elvis Dumervil.
As for his athleticism, I notice his ten yard split was a 1.60, or 81st percentile. Yes, the 40 yard speed matters, but when it comes to the shorter distances that count most in pass rush, Praise's acceleration is up there with anyone else's. Regardless, he's no athletic dynamo.
So why did such a good player go undrafted? Three reasons really and they're very simple.
1. He's 6'0".
2. He runs a 4.88.
3. He'll be 24 years old as a rookie.
It's really as simple as that.
He is unusually old because he missed 2 years of football while dealing with rape allegations that I'm confident in declaring turned out to be false. A woman accused him of raping her in his dorm room, I believe in 2012. He was kicked out of school immediately. Charges were filed. About 18 months later as jury was being selected the prosecution finally got hold of the woman's cell phone, where they found text messages between her and her friends admitting that the sex was consensual and she was claiming rape because he refused to be in a long term relationship with her. Just like that, charges dropped, he was allowed back in school, he resumed his football career.
Thing is, when you're seeing a guy who is playing a physical position like DL, and he is at least 2 or 3 years older than most of the guys he's going up against, and he looks good, scouts gotta be skeptical about that. Just as they should've been in the case of Margus Hunt. So the age thing was one strike going against him. His height was strike two, and his 4.88 speed was strike three. That's it. You're out. There's not even any need for tape eval at that point, as far as the NFL is concerned with respect to investing an expendable resource.
That said, don't be surprised if Praise makes the roster and is a good player.