Sparano did an awful job mixing the Jets offense with what Tebow brought in. Rather than integrating the two, he split it into 2. The Jets offense & the Wildcat with Tebow.
This whole poor practice player is misunderstood to begin with when you don't look at what's really happening. It's not too surprising when you have a spread option QB on your team practicing his own plays with the second team to not fit into a pro style offense that's being run by the first team.
McElroy and Sanchez ran the Jets offense. Tebow was practicing his wildcat plays with the second teams. Then he was probably asked to step in and take some snaps in the Jets offense. The results would be no different if things were reversed and you were running a spread option offense with non-athletic pocket passers as your back ups. Even Tom Brady would look awful trying to run read option plays.