Their corners aren't bad, remember the sliders affect specific players ratings, not the team's overall rating or the player's overall rating . I played a tough game against a 76 overall Browns team a few days ago in an exhibition lol
For example kellen moore is a 73 overall but his short pass is a 85, his medium pass is a 78 and his deep pass is a 59 I think, but the qb accuracy slider will affect those three ratings not his overall rating of 73.
The cpu AI system which is set by which difficulty you choose, will affect player's awareness rating and their traits. All Madden gives the biggest boost to these.