You seem to think a line in hockey is just the sum of its parts. That's not the case. Chemistry, playing style, tactics, all those things can either make a line better than the sum of its parts or worse. For example, neither Chimera nor Ward have particularly good offensive skills, yet together they generate a lot more offense than you'd expect from two stone hands pluggers. If you go back a couple years Hartnell-Briere-Leino was arguably the most effective line in the 2010 playoffs. Who on that line even knows what defense is? They should have been lit up, yet they actually dominated the competition. Semin is a much better player than Knuble yet Knuble was a better fit opposite Ovechkin and Backstrom than Semin.
Ovechkin-Johansson-Erat would have different dynamics from Johansson-Backstrom-Ovechkin. Mojo's defensive play would improve simply because he's better defensively at C. He wouldn't be a Selke player but it's no secret that his defensive play at C is better than at W, since he gets to use his speed more and his positioning is better. This line would also have 3 players capable of creating offense at a high speed, and having 3 players capable of playing at a high speed can patch up quite a few holes. Ovechkin would backcheck more (at least he should be asked), which he has shown to be capable of if the system requires it. Johansson can be better at carrying the puck through the neutral zone than along the wing where he always gets pinned along the boards and muscled off of it. You'd get more of a contribution from all 3 players and could have Ovechkin be more involved in the play, which right now he's not (and that's by Oates' design). Tell me, which one of Chimera, Grabovski or Ward is anywhere as good as Backstrom or Ovechkin? Which one of them is as good defensively (in a vacuum) as Backstrom? Yet amazingly enough they're a LOT better at even strength than a line with 2 far superior players and Johansson who himself is top 6 material.
Erat has had a few bad turnovers, yes, but career wise he's been a very good two way player. It's stupid to let the last couple of games dictate who he is rather than his whole body of work. If Ovechkin goes a couple games without scoring do we ****can him? And until his trade request is reflected by his play on the ice it shouldn't matter. He may be going through a rough patch (as players are sometimes known to do) but he's clearly not dogging it in any way. And he requested a trade because Oates kept ******** on him and putting him in a position to fail, if he starts to get a good opportunity to play the trade request evaporates.
Last, but not least, this also frees up Backstrom to be the man on his line, he can play at his own pace and march to his own drum without constantly having to play to Ovechkin's style. That makes the team harder to play against and in turn softens the minutes for Ovechkin's line. Backstrom can do whatever he wants without looking to force feed Ovie every five seconds. Likewise, Ovechkin can run around hitting people, deking, carrying the puck, rather than hovering around looking to get a pass from Backstrom. You have both of them contributing more because neither of them has to conform to the other and can take on more responsibilites. And fundamentally they're not the best fit for each other. Yes, Ovechkin can shoot at a high level and Backstrom can make plays at a high level, but together Backstrom has been reduced to a pure playmaker and Ovechkin has been reduced to a pure shooter, and both of them are much more than that. Backstrom can shoot more, Ovechkin can make plays at a high level himself, and carry the puck, etc. Ovechkin also excels in a high speed north-south game whereas Backstrom is as east-west as they come. They're not like the Sedins or Stamkos and St. Louis or Getzlaf and Perry where they were tailor made to play with each other.
