WAR does NOT show who is better. It shows which player is more valuable to their respective positions. Ike is better than Revere, but Revere may possibly be more valuable.
The only issue is whether it's an accurate measure. And especially in one year samples, it often isn't. And UZR, the defensive stat used by fangraphs, is especially suspect in one year samples. You need about 3 years to begin to have much confidence in UZR. Still, if you believed fangraphs WAR was 100% accurate, then you could argue that Revere has so far been exactly as good a player as Ike. Ike has been worth 2.878 WAR per 600 PA, and Revere has been worth 2.876 WAR per 600 PA. I had to go to the third decimal place to break the tie.
That's calculated using Revere's career .287 wOBA and Ike's career .345 wOBA. Comparing bats alone, that amounts to a 30 run advantage for Davis in 600 PA. That is, (.345-.287)/1.15*600=30.26. So Revere has made up 30 runs every 600 PA, about 3 whole wins, in everything else (mainly defense, base running, and positional value) for them to be equal in overall WAR. That's an astounding number. But yes, really elite defense and base running could be worth that much.
Still, if I use Bill James projections for 2013, he has Ike at a .371 wOBA and Revere at at .294 wOBA. That widens the offensive gap quite a bit, to about 40 runs. In that case, Ike might still project to be a full win better even if you buy fully into those defensive stats. In addition, the better way to do projections is normally to regress those defensive stats some amount, because they are less reliable than the offensive stats. So if you use projected defense (and base running), then projected WAR would move even a little more in favor of Ike.
That said, Revere does scare me a little. He reminds me of Ruben Tejada, in that he's a real "ballplayer" type. He's a real smart coachable kid who does all the little things. And that worries me because I think he really could learn to draw enough walks to be a decent lead-off guy. In which case, he might well turn out to be as valuable as Ike.
I don't think more valuable and being a better player is the same thing nessesarily. Obviously playing CF will give a better WAR boost than 1B because it is a tougher more important defensive position to play and not everyone can do it, but still when you are talking about who is a better player position aside, Davis comes out in front easily.
Revere as a CF will not be all that great, he is a -4 DRS player in over 1100 innings there. while UZR likes him more, it's needs a larger sample size. His arm comes up way short for the position.
Revere to me has way too many flaws. He can run and hit singles, that's all he can do. He has no arm, no power, no patience, and is just a average at best type of player unless he dramatically increases his plate discipline.
A sort of counter example, a guy who really is that good defensively, and who I think is a better player than Davis, would be Michael Bourn. Bourn gets on base at a good clip, is a legit +10 CF, and at least +5 base running. He steals 40+ bases per year. Despite a career .314 wOBA, he has racked up 21.4 career WAR, averaging 3.6 per season, and over 4.0 in each of the last 4 seasons.
If someone thought Revere was going to turn into the next Michale Bourn, that would justify valuing him as highly as Davis. But Bourn has twice as much pop and draws twice as many walks as Revere.