I remember, that the Dive+ TU mechanic was changed , to the way it is now. Especially with the (former new) card Shard of Readiness, the combination was seen as too powerful, and I think, it was rebalanced then. So Dive + TU doesn´t do, what you expect - it doesn´t double the Atk per copy.
I´m almost sure, that there are posts about this here in the forum, but I can´t find them.