He had 7 last season, in a year where he had to re-condition on the fly, he did a lot more blocking than he might have to this year, the team took until 7-5 to get the offense together, and the team didn't start using the TEs, RBs, and SlotWRs to best (Brady) effect until after the break. I do think Howard has the potential to take some of Gronk's TDs from him, But Gronk's numbers would theoretically be higher after ironing out those issues from last season.
I'm not saying I think it's a guarantee that he'll get 11 TDs, But it's the bet I'd play as of now, given the state of the moving parts.