There's no doubt Linehan has helped Garrett and the Cowboys. That's what OCs are supposed to do, right? The HC and all the coordinators on the staff seem to work well now, which wasn't always the case. We've got a good situation.
As far as the eyeball test goes, Linehan's play calling (at least the plays that we see getting run) is pretty clearly more interesting and innovative than Jason's plays were.
That's not to say the offense hasn't been effective the whole time under Tony (and now Dak). If you look at the points/offensive series over time, we've been in the top 10 every year under Garrett. As the OL improved and under Linehan we've been among the league's best. I'm ignoring 2015 for purposes of gauging the trends because I think most of us consider that season to be more the result of losing Romo/Bryant/Murray/Dunbar and having Weeden/Cassel and less the result of anybody's play calling.
Points/Offensive Series; (NFL rank)
2016: 2.54 (4)
2015: 1.56 (27)
2014: 2.62 (2) (Martin, Linehan)
2013: 2.25 (4) (Frederick)
2012: 2.01 (10)
2011: 2.02 (8) (Smith)