Agree we don't really know about Grissom, who has played in just 13 of the Sox 48 games this season.
But we know a ton about Sale. He's 35 and this is his 14th MLB season. For the 2012-2018 seasons, his WAR's were 5.8, 6.9, 6.6, 3.3, 4.9, 6.0, 6.9, which are pretty impressive. Then came 5 lousy seasons (2019-2023) with WAR's of 2.3, 0 (recovery from TJ surgery), 1.0, 0.0 (bicycle fall), and 1.7 with the Sox.
And right now his WAR is 2.1, his ERA 2.22, and he leads the Atlanta rotation in IP with 56.2 with 5 quality starts and a 7-1 W-L record. He's added a 4th pitch, a cutter, to his usually effective repertoire of slider, fastball, and changeup.
I think the tommy john surgery extends his effectiveness for at least 2 more years after this year--if not more.
So, yes, I think the Braves got a terrific deal in this trade, especially with the Sox paying Sale's salary this year.
Interestingly, the Sox gave up Yoan Moncada to get Sale, and Moncada never quite lived up to his hype. 2 good years, 2019 and 2021, with WAR's of 4.6 and 4.0.