Mazi was definitely a need for this defense.
People won't like to hear it, but DQ's front seven is pretty similar to Rod Marinelli's front seven. They both love to play undersized, high-energy pass rushers and run huge amounts of stunts with them. Quinn really likes to overload one side of the formation as well.
On top of that, DQ doesn't really like deploying traditional linebackers. He basically uses box safeties for that role. Again, trading size for speed underneath.
So he needs at least a couple run stoppers in there. He's going small up front, and sacrificing gap integrity to set up pass rush games. You need a big NT who can put a dent in the line, or more physical teams like the Niners are just going to push your entire front off the ball.
In Seattle, Quinn had Brandon Mebane on the nose. In Atlanta, he had Grady Jarrett, who was sort of a unicorn as an excellent pass rusher and run defender. Here, he didn't have anything besides the usual Garrett-era Nick Hayden types. Even pulling Johnathan Hankins basically off the scrap heap made a big difference, so I totally get the need for a young and talented player there.
The need is there, the scheme fit is there, but I just did not like Mazi as a prospect. It's like Taco Charlton... DE was a huge need when we picked him, but drafting a bust DE didn't fix that. Rule zero of the draft is "try to pick a good player", and I just did not think Mazi is one.
He's young. We'll see how he develops.