What is the idea of 5...Ne7 in Ruy Lopez Exchange?

That's not a very good move. Bc5 and Qd6 look better to me. Even a move like Bd6 or f6. Ne7 doesn't accomplish anything. Maybe there's some idea with Ng6?

I stand corrected

I did some digging on Ne7. I hope this is useful.

• Ne7 is the variation that became popular in the early 1970s.
• Black covers the e-file and thereby indirectly defends the e5-pawn.
• The best response--for those playing for the win--is 6. Nxe5.

Here are a few sideline variations presented in the Panczyk & Ilczuk book which show that anything other than Nxe5 probably leads to a draw.

A: 6. d4

(a)(1) 6...Bg4!?

(a)(2) 6... exd4

B: Na3 (plus 6. c3 / 6. d3)

(a)(1) 6... Bg4!?

I guess maybe 6. Nxe5 is the best test for the line but it's not really that much into the spirit of the Exchange.

The way I've always played it was that White gives up plenty early (The WSB, exposed KP, and totally undeveloped Qside) but can have a winning endgame if it can go that far. The problems for Black are how best to keep the B pair and where to make them effective. Plus how to best hold the e5 square, a key target for White's plan. Here ...Ne7 ...Ng6 and ...f6 (without ...Nf6) handles it seemingly well.

Though 6. Nxe5 does seem to take care of the e5 square, it might not be best with all White's weaknesses still remaining.

Samuari-X's 6.c3 or 6.d3 seem fine for White and fitting in with the plan. Especially notable is the getting rid of one of Black's B's without too much weakening which I've always found is a nice plus in the variation.

I've also noticed, though I may be wrong, that the Exchange maybe isn't best for blitz. The Black B's can be tough to handle and usually need some think time by White plus how to repair White's starting weaknesses in an advantageous way probably requires some additional thought. Black's play is generally much easier on the clock.

The problem with 6. Nxe5 is that the Fork Trick works, now that the e-File is clogged up by a Knight (5...Ne7). Once White's e-Pawn is gone, White can forget all about an Opening advantage. Of course, it might be regained if Black errors; but Black can say that too, and he can say it already, hence equality.