We all love to debate on Isaiah Thomas and if he is a starting caliber PG. Some say he is a top 10 NBA PG while others say he should be a 6th man. The biggest knocks on Isaiah's game are his passing and his defense. I will be focusing on his defensive numbers in this post.
I took the liberty to add up what every starting NBA point guard has scored since Isaiah has taken the reigns as starting PG. Since the Rudy Gay trade the starting point guard for the opposing team is averaging 14.89 points per game. While Isaiah is averaging 21.5 points per game. The top 30 point guards in scoring, average 12.8 points per game. So Isaiah gives up roughly one extra field goal per game than average on defense. Isaiah may not be an elite defender by any means but scoring nearly 9 points more than you are giving up isn't bad.
In Isaiah's last 10 games his defensive intensity has seemed to improve to my eye so I looked at the numbers and in the last 10 games he is giving up 13.2 points while scoring 22.7 points per game. In his last 5 games he is giving up 10 points per game while scoring 23.2 points per game.
I decided to also look up the last 10 games of some other starting points guards and what the opposing teams starting point guard was averaging against them.
Mike Conley in his last 10 games gave up 11.7 points while scoring 18.3 himself.
Jeff Teague in the last 10 games is giving up 12 points per game while scoring 11.7 himself.
Kyrie Irving in the last 10 games gave up 12.8 points per game while scoring 20.3 himself.
Stephen Curry in the last 10 games has given up 16.1 points while scoring 25.4 points himself.
John Wall in the last 10 games has given up 18.8 points while scoring 19.8 points himself.
Damian Lillard in the last 10 games has given up 20.8 points while scoring 21 points himself.
I understand this isn't a perfect stat because of many reasons, but the point of all those numbers was to show that in the current NBA points guards put up a lot of points on whoever is guarding them.
All stats were gathered from Basketball Reference's game logs and added into excel.
Update: For Kings and Country asked the FG% of Isaiah's opponents. In the last 10 games Isaiah's opponent shot 38.7% (43 of 111).