Really? I see Heyward as a complete 4-3 DE who can be very stout against the run and rush the passer with quickness and strength, play the 3-4 DE, or even slide in and play a 3 technique in a 4-3. I don't think Griffen has that sort of versatility. He is a weakside 4-3 DE who could maybe play 3-4 OLB.
Heyward and Adrian Clayborne are going to be top 5-15 picks next season. They are two of the most versatile DEs I've ever seen. I really hope the Bengals don't get one of those guys. Griffen doesn't frighten me. But, I could very well be wrong.