In 2014 Hanley had a 135 wRC+ and was a -15 UZR/150 defender at SS. 3.3 fWAR.
At 31, and with a 190 wRC+ in 86 2013 games, his bat should have held steady, for the most part.
Hypothetically, according to the defensive spectrum and Saber dogmatism, a -15 shortstop should be a neutral zero run left fielder.
Perhaps a good scout could have foreseen him turning into a -30 run LF, based on his body and some of his eccentricities, but it seems pretty random to me that he's that bad. He's handled shortstop for most of his career and while he has never been good he's always been a viable player there considering how well he hits. Him in LF making Mark Trumbo look like Alex Gordon is pretty f***ing crazy random.
The offensive decline probably has something to do with the stress of sucking in the OF and being preoccupied with trying to figure that side of the game out.
It was a weird f***ing signing from multiple angles though. Why pay such a big ticket price to a career SS and then plop him in your wonky LF, when your team already has a s*** ton of OF depth?