Not really. He has raked LHP in his career. IF (and its admittedly a big if at this point) the Sox add Machado and Joc, Guyer is a very nice platoon piece. If he sucks in ST or early in the season, so what you cut him. All three of Palka, Engel and Delmonico have options.
Against RHP (post Eloy arrival):
Jon Jay RF
Joc CF
Machado 3B
Abreu 1B / DH
Eloy LF
Moncada 2B
Alonso DH / 1B
Castillo C
Anderson SS
BN: McCann, Sanchez, Leury, Guyer
Palka starts the year as the LF, goes down to AAA with Delmonico and Engel once Eloy arrives. All three guys have options.
Against LHP (post Eloy arrival):
Jon Jay CF
Alonso DH / 1B
Machado 3B
Abreu 1B / DH
Eloy LF
Castillo C
Moncada 2B
Guyer RF
Anderson SS
BN: Joc, McCann, Sanchez, Leury