Howard has been almost as bad, if not as bad as Ward over the last 3 years.
Howard since 13-14 has a .910 save percentage, Ward has a .906 save percentage since 13-14.
The biggest difference is that Ward has sucked since the 12-13, while Howard didn't start sucking until 13-14. Not to mention that Howard has has an exceptionally strong start to 16-17, while Ward has had a rotten and disastrous start to 16-17, even by his own standards in recent years. I don't expect Howard to play this strongly the whole season, I think he'll regress to a .910 goaltender. Ward will likely progress to a .905-.910 goaltender, I don't expect him to sustain quite this level of horrid play. Although who knows, he's been terrible for years now and is bound to completely seize up and send a rod through the pan.
All in all, trading Ward or Lack for Howard is kind of like trading Ward or Lack for another Ward or Lack. Howard in 2016 is much more similar to Ward than people seem to think.
If it was for just this year, it might be worth the try in giving Howard a change of scenery. 2 more years after this (I think?) is too much term left on a goaltender that they're hoping isn't as bad as he's been for the last 3 years. May as well stick with 2 more years for Ward, at a much friendlier cap hit. Unless Ward declines even more or Howard plays better than he has in 4 years, the difference in the two is not significant. It's just more of the same for the Canes, which is more **** goaltending that completely murders them and takes them out of games, despite a pretty decent system of play.