Well, they still have Rojas. Mercado's not much of a bat either, is he? And they just weren't comfortable throwing Kennedy into LF. I think if it wasn't Wilson's job they would have been more aggressive, whether about acquiring someone else or being willing to add Mercado or Arroyo to the 40.
Also yesterday's LH starter was great against everyone. Hopefully this also allows Marsh and Kepler to get better. Not seeing LHPs as often is one of the reasons hitters struggle against them, just as much as the arm and bat angles. And Kepler got to the reliever (as did Schwarber).