It's not a bad move. We can use some depth going into the second-half. The positional versatlity is key.
2nd base wasn't a huge position of need. With Chapman red hot, Espinal and Biggio are relegated mostly to 2B., where they are doing fine.
OF we can use more help though. Springer/Gourriel, Teoscar are great, but we can use a quality 4th OF, and Merrifield certainly qualifies for that.
The trade is only disappointing because I think everyone wanted an elite bullpen guy (Bass is decent, but maybe a little underwhelming), or a decent starter (someone better than Mitch White).