His best three year stretch for the Jays Carter put up 9.5 fWAR over 2050 PA's (before putting up 5 negative fWAR seasons).
Some Blue Jays Comparables.
Jose Reyes 2 years (1050 PA's) 6.3 fWAR and run out of town
Alex Rios best three years 14.2 fWAR (run out of town the next season).
Shannon Stewart best 3 years 11.7 fWAR (run out of town the next season).
Kevin Pillar's first three full seasons (1825 PA's) 7.9 fWAR
Vernon Wells last three seasons before being run out of town 4.7. His best three year stretch 12.9 fWAR
Yunel Escobar's 2.5 seasons in Toronto (1500 PA's) 6.3 fWAR
One thing I will say for Carter is that he played in an era where they would never move an athletic guy like him at DH, so some of his negative defensive seasons could have been reduced.
If I had to name the 10 greatest Blue Jays (during their Jays tenure) of all time Carter is not on it. I'm not certain he is on my Jays all-time OF top ten (Bautista, Wells, Moseby, Barfield, Bell, Rios, Stewart for sure ahead)
Essentially Jays have a history of running people out of town at the first sign of struggling no matter how good they were prior...unless you hit a huge HR.