If you haven't figured it out yet, the duties of the baseball manager don't actually involve managing any baseballs. You don't have to put them anywhere, or find them—in fact, you're the only person in the dugout who doesn't even ever have to touch them.
Maybe the job should be called baseball avoider instead?
What the baseball manager actually manages are the team's players—on the field, in the dugout, and in the bullpen. Major league managers have tons of pull when it comes to decisions made on the field: who plays where, who pinch-hits, who sits, and who steals, bunts, or swings away.
If the coach thinks a player has the wrong attitude, or was out partying too late the night before, they can make them sit on the bench for weeks at a time. They're also heavily involved in drafting players, signing free agents, and all the other steps along the way toward building a championship team—or at least a team that doesn't finish dead last. For some perennial losers, that's just as good.
Of course, some of this authority goes out the window when dealing with superstars. Superstar salaries and superstar skills can lead to superstar egos, which often includes disagreeing with the manager openly and vocally. It's a trade-off; if your team's fighting for a playoff spot, fifty home runs and a bad attitude might be worth the headache.
How do you handle it? We don't know—that's why they made you the manager. Handle it.