I think it's just being realistic
They're not trying to catch the Yankees
They're trying to field a better-than-500 team for 2018, a team with a (perhaps small) chance of competing for a wild card. They don't want to trade any top prospects because they know they'll be in good shape in 2-3 years if they keep them, and they don't want to hand out any bad contracts. So they're filling spots via smaller trades (Eg. Grichuck) and 1 year vetarean free agent deals (Eg. Granderson). It's a fairly "safe" plan I suppose.