By percentage it's Hartline drops 16.7% of the passes thrown to him, Marshall drops 14.7% of the passes thrown to him and Jones drops 13.6% of the passes thrown to him. None of those are particularly good and you could argue that if Jones was thrown to more he would have as many or more drops than Marshall but in this instance he's a more reliable target than Hartline.
As for Jones and the "pass happy offense" he was the 4th receiver so he doesn't get on the field often, certainly not as often as the #2 receiver in Hartline, so despite Hartline being on the field more he was thrown to less...you can take that how you want. Could be Hartline is not very good at getting open, could be Marshall demanding the ball from his QB, could be a combination of the two. But then again, Hartline was 4th in catches on his own team despite being the #2 receiver....Marshall obviously was 1st with 81 catches, Bess was second with 51 catches and Bush was 3rd with 43 catches.
As for production Hartline caught those 35 passes for 549 yards, a 15.7 ypc average...and that's good...the bad is he only caught 1 TD (and has only 1 TD in his last 26 games). Marshall had a heck of a season as far as average goes, he caught 81 for 1214, a 15.0 ypc average for a guy that normally averages around 12 ypc....and he had 6 TDs which is about average for him. He has 34 TDs in 6 season...he's never been a big time scorer, he's career high is 10 TDs in a season back in 2009 and the 1214 receiving yards was the 3rd best of this career. James Jones, in limited playing time last year had 38 catches for 635 yards, a 16.7 ypc average and he scored 7 TDs...the same as Hartline and Marshall combined. He scored 5 TDs in each of the previous two seasons.