I am certainly no talent evaluator, and Garcia may come with an extra couple years but those years are likely to be league average hitting and poor defense (he is -14 DRS so far this year). I could be absolutely undervaluing him, but this seems like a massive overpay. Ryan Gusto, a back-end starter with 6 years of control, alone should be enough to make this trade happen, unless you think last year was a breakout year and not a fluke that I think it was. Or taking Gusto out seems to make this a reasonable trade. Just my opinion
He was a 3 fwar player last year and he has been unlucky with the bat this year (xwOBA .372 vs wOBA .317). Your opinion is certainly valid, it could be a big overpay depending on how you value the various pieces. Dezenzo is hurt, Blubaugh has looked awful the last 6 weeks, Baez is having a lost season so far. If their stocks were all how they were in March, I don’t think Gusto would be needed.
LH Bat Ryan O'Hearn is absolutely the perfect bat to add. He plays 1B and OF, we get versatility plus one of the best bats vs RH pitchers in the entire league. He's a rental but he would only cost $2.7 million at the trade deadline. It would cost us little to get him. Baltimore is certainly selling at the deadline. High Leverage Reliever Aroldis Chapman has been there, done that. He's having an outstanding year. Boston will sell at the deadline. He's on a 1 year deal, again a fairly inexpensive trade. Can you imagine Abreu and Chapman as your choices to set up Hader. That can win you a championship.