(2) HV4.5 motors 1 is considerably slower. Worn out rotor?

[Gee]

I got the same setups (HV4.5) in two different RCs. My recently finished evo was notacibly slower then the emaxx. I swapped the esc and motor and now the evo is the faster. THe RC are setup the same 72/14 with the emaxx trannies locked in second and running (2) 2s2p. It has to be the one motor. It came with an esc off ebay. The two esc were both replaced with remanufactured ones with in the last two months and the other hv 4.5 motor was bought new september. I replaced the bearing in the older motor last month while I was waiting on the esc. Should I have replaced the rotor also? Anything else in a brushless motor that could cause a performance issue?