oWAR + dWAR does not = WAR. There is a positional adjustment to oWAR and dWAR that is double-counted if you simply add the two numbers.
That said, you are correct that Manny’s best rWAR year was his age 22 season. His rWAR total that year was 7.5, not 8.0. By fWAR, 2022 was Manny’s best year. In any event, I think it’s fair to say Manny’s still in his prime, based on his excellent 2022 campaign.