Yeah but you have to score or assist to win games and Adams, despite running around a lot, didn't do enough of that. Is Adams going to get 15 assists this season? Doubt it.
He played mostly as a wingback last year. If he scored or assisted more from there, he'd be in Europe right now. Assist activity was intentionally focused on Sacha last year (and it didn't get us where we wanted).
Will Adams have 15 assists this year? Probably not, especially if he won't be taking set pieces. HENRY never had 15 assists iirc.
Will Adams contribute a ton more than Sacha did on defense and in the press? One hundred percent yes. He'll score more goals than Sacha did in 2017, too.
But if your one and only measure is the number of assists without any other considerations, sure, letting go of Sacha will always seem like a huge mistake.