I feel it's worth mentioning something that people need to consider when you're using WAR to compare players and also when you're talking about whether to move Sandoval to 1B or not. WAR is calculated using positional adjustments, which are a good way of determining the overall ability of a player or when comparing players who play at different positions. It's very good if you're looking at two players in a vacuum but troubles arise if you'e doing a comparison in a team context.

In the Giants situation that can cause trouble if you're comparing a 1B and a 3B using straight WAR. The reason for this is that 3B get a 1.5 WAR boost over 1B because they can play 3B and so they should. In the Giants situation they have a player who can play 3B (Sandoval) and so the positional effect isn't anywhere near as big.

How big is the effect? Well that depends on how Sandoval's defense rates at the two positions. So far he has a UZR/150 of -3.6 which is only in a small sample size, but seems reasonable. I'll take that as his true level for the moment but you can adjust accordingly if you disagree. In order for the positional 1.5 WAR adjustment to be true, Sandoval would therefore need to be a +11.4 1B. Now that just isn't feasible as no 1B is that good defensively and so the Sandoval will "lose value" at 1B.

Now how good defensively will Sandoval be at 1B? Well he should be pretty decent although i don't think he's going to a league leader defensively. Three examples of well renowned defensive 1B are Adrian Gonzalez, Mark Teixeira and Casey Kotchman, they have career UZR/150 of 0.1, 1.7 and 4.4. They average to around +2 per 150 games and so lets say that Sandoval is above average and can put up a UZR/150 of around 1.4 (as that's a convenient number).

That means that that Sandoval will gain around 5 runs defensively from the move to 1B which is nowhere near the 15 runs the positional adjustment provides. What that means is that if we were to sign a 2B/3B his actual effective WAR (as in how good he'd make the team) is quite possibly 1 WAR less than is actual stated WAR. So a free agent 2B/3B who you think is a 2.5  WAR player might actually only effectively be a 1.5 WAR player when compared to a 2.5 WAR 1B. Or the improvement over Garkokawa might seems like it's worthwile and a 1.5 win improvement when actually it's only a 0.5 win improvement. So a pretty rough rule of thumb is to subtract 1 WAR (or however much you think) from the value of a 2B/3B if you're using WAR, to get their effective value to the team.

Now the numbers aren't exact and you can argue about the specifics but if you're using WAR and the like you've got to consider the effect on the team as a whole and not just on the single players. The Giants may not really understand how moving a player down the defensive spectrum has an effect on the team, and assume that it doesn't matter whether Sandoval plays 1B or 3B but the reality is that the two players you're comparing aren't being compared to the same baseline.