Yes, Leury is a good player to have on the roster. Nice to have, trust the process, etc. I believe that the White Sox intend to get a better second baseman still.
Here's the problem, as I see it:
When you're operating on a limited budget and prices are not fixed or determinable, it makes NO sense to buy things you DON'T need before you buy things you DO need. This deal (years/dollars) is fine in a vacuum, but it's only fine in context if it comes on the heels of having your necessities covered. This is a deal that should have come at the end of the offseason IF the Sox found themselves with budget remaining.
Everyone pretty much agrees that the Sox have three substantial roster holes to fill: (1) RF, (2) 2B, (3) SP. As it stands the White Sox have now committed (conservatively) at least a third of their likely budget space (~$12.5m to Graveman/Garcia) and filled NONE of those holes. This reduces their leverage for filling those holes, and if they fail, it will be at the expense of the major pieces for the benefit of covering the minor "nice to haves." If Sox ended up having to overpay for a starting caliber RF/2B and it left them "scrambling" for a bench piece, they would be in drastically better position than if the opposite were true.
To me, to make this deal on this date is yet another inexplicably inefficient application of limited resources. They may very well fully intend to acquire real solutions for their problems this offseason, but they've put themselves in a great position to fail at doing so. Maybe the CBA will shake things up and make this a good move, or maybe they'll pull the right deals off anyway. but it won't be because it was "smart," it'll be because it was lucky.
It's finally looking clear to me why this team seems to miss on its targets so frequently. They're getting in their own way and I can't understand why.