I know a lot of people complain about there being too many INT's but people have to realize that once you start adjusting the gameplay sliders, everything changes.
I play on Legend as is and will usually get 15-20 INT's a season which isnt bad at all. Some games, I'll get 2, 3, 4 and even 5 INT's but then I'll go several games in a row without any INT's at all.
On offense, the only way that I usually throw a lot of INT's is by forcing the pass when I should throw the ball away instead.
Personally, on Legend as is, the DB AI isnt good for the player when it comes to getting INT's and I hate that. When the ball is thrown right to my damn safety's chest, it should be an INT.
If I start getting more then 20 INT's in a 16 game season on Legend with 5 minute quarters, then I would say that its slightly high but otherwise, I think it's right at the average in the NFL.