From 2009-11 just 22.4% of the Rays opponents ground balls became hits, compared with 23.6% for an average American League team. That difference may sound small. But it amounts to an advantage of 21 hits per season – which translates into a 1.7-game improvement in the teams won-lost record.
Signing a player on the free-agent market who would help the club by a similar amount would cost over $8m. Baseball In The Midst Of A Defensive Shift Revolution - Business Insider