Yaz was the most significant player in the history of the Red Sox. Williams ws the best hitter of all time, but Yaz did everything else much better. Where Yaz vaults to the top of the pack for me is that the 1967 team revived the moribund franchise that was considering leaving Fenway and Boston. The trajectory of the franchise changed with that season, and that was the season of Yaz. Beyond 1967 the Red Sox remained as a winning and competitive franchise with teams built around Yaz. After 1967, the Sox failed to field a winning team only once for the rest of Yaz career -- in 1983 (Yaz's last season). From 1967 to 1982, they finished above .500 for 16 straight seasons. That is the longest streak in the history of the franchise.
Yaz was the leader on most of those teams. He is the player who made the most significant contributions to the Red Sox in the era that turned the Red Sox franchise around and made them not just relevant again, but beloved. The Red Sox need to commission a statue in his honor at Fenway, because I truly believe that Fenway might have been long gone had it not been for Yaz. For that matter, the Red Sox might not be in Boston either. I'd like to this done while he is still around for the dedication.