He started there last year after looking good in camp/preseason, so I wouldn't outright dismiss it.
Our third line isn't that anymore. It's a grindy defensive line that has no skill or creativity.
The primary issue is Rossi (square peg) being forced into a situation where he's playing with grinders and guys with no skill or creativity (round hole), regardless of what line it is.
The simple fact is that Rossi should be judged on how well he can perform with smart and skilled players. If we had enough of those to fill a third line, starting him on the third line wouldn't be an issue. But we don't, which means he's going to need to start on the second line. Because it's not about the number of the line he's playing on, it's about the players he's playing with being conducive to his success. If the wingers on this line were Coyle and Nino instead of Foligno and Gaudreau, no one would be up in arms about him playing on the third line.