There's a lot of hype about Howard and the effect he'll have on the Bucs offense. There's talk about how Howard makes this the best Bucs offense ever, etc. Yet his impact will be limited to as a part-time player.
This isn't a knock on Howard, it just takes tight ends a year or two to learn the position and become effective as both passers and blockers. Howard will have an impact, but it will be as the no. 2 TE.
Up until 2014, only 26 TEs had exceeded 500 yards. Only two rookie TEs have scored more than 5 TDs (Gronk & Hernandez).
Gronkowski's rookie season is likely unattainable for Howard with 42 receptions, 546 yards, and 10 TDs (2010).
And that's OK. If Howard doesn't hit 500 yards or 5 TDs, he's in good company with players like Olsen, Gates, Kelce, and Witten. Tony Gonzalez had 576 yards and 3 TDs, while Jimmy Graham had 356 yards and 5 TDs.
Howard has the skillset to turn into an elite TE. And he'll contribute as a role player and backup. But don't expect more than that.