Irving has shown he can do both. Gregory won't be a long shot since he has something we need on the edge, speed.
I think your homer goggles are on.
Irving is better stunting, moving, etc. He's not a pure edge player. He often looks his best from the 3 Tech spot, which is his best position.
I don't care how fast you think Gregory is, speed is useless if you struggle with the contact, etc. he hasn't seen in 2 years. There is no chance the Cowboys just give him a spot on the 53 if he can't actually perform simply because he's "fast".
This Cowboys front seven is far from being a dominant group. And that's without talking about the LBs, which are still huge questions - we have no idea what kind of pro LVE will be and Smith is a total unknown himself at this point.