Lol. Just like the majority of the fans in the league I see. Don't know why this misconception is out there. Maybe cause he's not a household name / as sexy as a Sherman or Peterson or Revis? iunno, but I shake my head every time at this....Butler is doing everything+more than what Revis did for us. Has truly emerged as bonified #1 CB.
He's not "overrated" nor "underrated" imho, he's just 'rated'. Top5-10 CB in the league. Same age as Peterson, relatively young at 26, and best years are still ahead of him. And if I'm being honest, he's only overrated for people like you who only view him as the Butler who got the SB clinching INT. Seems that's all you/they know about him and haven't really seen him since and just judge him as overrated off that. That's not his fault hahaha.
...vast majority of the time he won't have a game where he allows over 100 yards and on average allows ~45 yards give or take. That one game versus Pittsburgh last year is a bit deceiving and the only game he allowed over 100. Most those yards were just screens to Brown and garbage time yards/TD. He was also the only one last year to completely shut down OBJ. The 1TD was McCourghty's fault too. Butler had short coverage that play and let OBJ pass him knowing Devin was double covering the deep ball. He messed up his assignment and Butler got faulted for it - wrongfully. That same game, he also swatted a sure TD out of OBJ'a hands in the end zone. He went up, caught it and everything; going down tho, Butler maneuvered and positioned himself to break it up even when the balls was firmly in Beckham's hands.
...Butler is just an all around sound defender. Great athleticism, reading of the game, physicality, instincts, and anticipation which usually messes up whoever lines up opposite of him...not a coincidence he was named a pro bowler. Fierce competitor who doesn't shy away from anything. One thing I love about him - some people back down when given a tough assignment, he seems to elevate his game those moments. Heck of a scrappy player.
& FWIW, he hasn't allowed a TD this season. Hope that answers your question