I don't now if the Red Sox see it as an issue.
Devers and Casas don't have issues with splits. Anthony and Teel have been good in MiLB.
Duran, Hamilton, Abreu, Yoshida and Mayer have had their issues. Masa was good last year. Duran has been a little bit better than he was in the past. Abreu has a big split and they really avoid playing him against LHP. Mayer may get better, but split issues have been more of a concern as he's progressed in the minors.