EHern led all NL second basemen last year in Range Factor, per b-ref. In his career he's played more games in the outfield than infield, with over half of those in centerfield. His versatility could keep Verdugo in right and Beni in left, while keeping center warm for Duran or Jiminez.
At $7M per, it's the costliest signing of the Bloom Era -- but justifiable as a two-for-one investment in both a second baseman and centerfielder. If the Sox keep Beni, this may be the last position player acquisition (unless they add a really cheap outfield glove).
Bloom should focus the rest of the payroll on pitching... where KeyKay is only 0-1 lifetime with an 81.00 ERA.