ROTFL Every time you think Gravis has run out of ways to embarrass themselves, you get something like this poll. On a related note, this poll over-samples folks who are 50-64 by roughly 20%, over-samples evangelicals by about 7% relative to the state's actual demographics (not to unskew or anything, but it seems worth mentioning).
Yeah, Gravis is an awful pollster, but I wouldn't call them Republican-leaning or anything like that - just look at their Nelson +25 polls, lol. I'd say that this is the third most likely Democratic-held seat to flip (after MO and IN), but again... not because of this poll.
I also just took a look at the RCP average in 2012... and no, there wasn't even one poll that showed Mandel leading Brown, and certainly not a Gravis one. There was one that showed a tie, though.
Brown can't take anything for granted, but that being said, he should be fine. And I really don't see how one can possibly argue that he's more vulnerable than Heitkamp and Manchin. This is a solidly lean-D race, especially with Mandel as the likely nominee. Btw, it should be pretty telling that Husted, DeWine, Taylor, Renacci, Stivers, and Yost (to say nothing of some of the higher profile Republicans in the state legislature) all showed almost no serious interest in running against Brown (just like no one except Mandel showed any interest in 2012, not even Kasich). It remains to be seen whether Tiberi will run and if he somehow made it past the primary (hard to see happening, but certainly not impossible), he'd be a much stronger candidate than Mandel (although Brown would probably still win), but the fact is that Brown is pretty strongly favored to win re-election (in addition to being about as close to entrenched as a liberal Senator can get in Ohio's current political environment) and almost everyone in Ohio politics knows it. Tbh, if Mandel thought there was any room for him in the gubernatorial primary, I don't think he'd have run for Senate either. I mean, Brown can't take anything for granted, but he's starting the race with a clear advantage.