Season 3 remains my least favourite of the seasons, and I think the character introduced by it have had far shorter shrift characterisation-wise than those introduced before and after. It must be said I think season 5 is a leap in quality better than season 4 and I'm not sure why that is, given they were produced back to back, but maybe it is, as you say, that season 4 was trying to do too much heavy-lifting with the new characters. I didn't have too much trouble with the time scale of the Connor/Burton thing. If Burton were a better manager he wouldn't have put so much effort into separating Connor and Abby, and in preventing Connor from having a life outside the job. While it seems slightly surprising that Burton should have risen as far as he has without such skills, as a character point it's quite interesting and potentially would have allowed him to be an antagonist but not a villain.