Maybe they think they could get his extension even greater? It’s been mostly stagnant since his excellent 2019 season (coupled with a 1 mph drop in FB velocity). He also lost a few inches off his vertical release point in that time.
Easier said than done — and I don’t know how long these guys’ limbs are — but maybe it’s possible? It seems clear that it’s something they worked on with Pivetta, who gained several inches in vertical release point and extension point after we acquired him.
Pivetta, 2019: 6.23 avg. ft vertical release point | 6.3 ft. extension
Pivetta, 2021: 6.58 | 6.6
Pivetta, 2023: 6.59 | 6.8
Pivetta is 6’5”, one inch shorter than Giolito, and has a greater extension. But everyone has varying capacities, obviously. Spencer Strider is (generously) 6’0” and has a 7-foot extension point. Nick Robertson, Kenley Jansen, Pivetta, Paxton, Eovaldi, Wacha, Schreiber and of course Whitlock all have ++ extension points, so the Sox seem like one of the teams (among many) that have focused on it.