Jon Kitna was one of those career Journeyman QB's u don't really see these days kinda like a vinny Testaverde he was a top 20 QB in stats most years but always played on bad teams Seahawks, Bengals, Detroit and usually got replaced by a first rounder career 77-78 QBR passed for almost 30k yards. His problem was TD/INT ratio 169/165 most of his problems were the teams he played on terrible offensive lines and WR's. Put him on a semi decent team and he is a decent starter. the only really great WR he ever had was Chad Johnson and that was during Chads first 2 years. His best statistical year came with him throwing to such legends as Mike Furrey and Roy Williams in DETROIT.
If his Kid has Half the arm talent he had he will be a good one. His father will be a bastion of knowledge because he mentored a couple good QB's Romo and Carson Palmer and is currently QB coach for Dallas Cowboys.. Also if you look at his track record he went to teams and ended up mentoring or getting replaced by first round picks (Dilfer, Palmer, Stafford) at all but his last stop (Romo). One could argue all but one of those guys was well above average at worst. Undrafted free agents dont keep getting signed for 14 years if they are no good.
TLDR version Kitna was far from a scrub and Honestly if he had ever been put in a decent situation with a good team he would have had a very different career..