Average wise he's not great, but like I said earlier the ban of the shift will likely help that. On base percentage is more important, and his career OBP% is higher than Kepler, Urshela, and much higher than Byron Buxton. On a one year deal, it doesn't really matter if Gallo is making 11 million or 8 million.
I'm not sure why people continue to complain about Urshela. He was the stop gap until Miranda became the every day 3B, which he is now. If they keep Arraez, his only real position is 1B or DH. That doesn't leave much room for Urshela.