Andy Dalton is PFF’s 2nd highest graded passer this season

Hasn't Lawrence also played in 4 more games than Dalton? So if Dalton is averaging 1.5 TDs a game along with 218 yards...that would give Dalton 872 more yards and 6 more TDs to go with his current numbers.

Let's put it this way:

Lawrence 66.0% comp. avg, 251 yrds/gm 1.7 TDs/gm .5 INTs/gm
Dalton 66.8 % comp. avg, 218 yrds/gm 1.5 TDs/gm .63 INTs/gm

So, how's Dalton rated that much higher than Lawrence?