Engvall is fine in a vacuum and could certainly find a role on a good NHL team. The problem is when your bottom 6 is shaping up to be Engvall, Mikheyev, Kampf, Bunting, Spezza, Simmonds, and/or Brooks, then you're probably in contention for the least amount of secondary scoring from your bottom 6 in the league.
A Mikheyev-Kampf-Engvall line for example looks like a pretty solid shutdown line, but with virtually no offence. So you'd probably want to compliment that with a depth scoring line, but Bunting-Brooks-Spezza isn't exactly producing the type of offence Tampa got from the Gourde line, Washington got from the Eller line, St. Louis got from the Bozak line, Pittsburgh got from the Kessel line, etc (when looking at the 3rd lines on some recent Cup winners).