Stray note #2 - The RISP is critical though. How many times has Joey hit in big situations. How many rallies has Dom killed. It shouldn't be minimized.
Stray note #3 - Sounds like Adon could be an effective middle reliever and a lousy starter.
What Joey has done with runners in scoring position this year has really maximized what his hitting this year could produce. IOW, he's not had a good year for a middle of the order bat, but when he's hit, it's counted a lot. Whether that's his true level or not, it's not something you can count on as much as a guy who is consistently good. For example, last year, he was .220 with RISP. Which is real going forward? Probably something closer to his actual talent.
As for Dom, the comparison is more a measuring stick for Joey than it is praise for Dom. Remember, the first 1/4 of the year or so, this guy had an ISO comparable to Pete Gray. The only praise for Dom is that, since then, he's more or less an average hitter. We all got pretty poisoned on him, and, no question, his production with runners in scoring position is lousy (.196 AVG, .556 OPS).
Since May 1, Dom is .266 / .335 / .387, 98 wRC+, with 9 HRs; Joey .276 / .327 / .408, 100 wRC+, with 10 HR. Awful tough to tell them apart, but for RISP.
As for Adon, it sounds like he'd benefit a lot from an opener. Pitch Ferrer or Garcia in the first if the top of the order is lefty-loaded, or throw Ward or Machado if it righty heavy, then bring in Adon to start the 2nd. That way, 3rd time through the order is against #5 or #6 in the order and not the top. At that point, watch him like hawk and pull him when he gets in trouble. Ideally, this gets you to the 7th when your bullpen A can take over if you have a lead.