Wondering about a manager's decision

Sometimes managers make moves that can get second guessed. Actually, that seems to happen with any move a manager makes that didn't work. I am second guessing Juan Samuel's decision tonight to bring in Alfredo Simon to pitch in the top of the ninth. It was not a save situation. In fact, Florida led 6-5 as it came to bat in the ninth. The Marlins would add a run and four hits off Simon, a big insurance run and go on to win the game, 7-5. This move had little to do with the O's loss, but it seemed like a move that the O's did not have to make. David Hernandez came on in the top of the seventh and got two outs to escape a jam and then he fanned two more batters in the eighth. Hernandez was throwing real well and threw 17 of his 21 pitches for strikes. Meanwhile, the O's scored once in the last of the eighth to close the gap to 6-5 and had some momentum going. Then Florida added a big run in the top of the ninth. It seems under two managers this year, there have been times when a relief pitcher was throwing very well but the club turned it over to the next guy who was not as sharp. It happened again tonight. It sure didn't cost the O's the game, but was just a move that didn't need to be made. By the way, it's almost too soon to criticize anything Juan Samuel does when the guy has only been on the job for 17 games. And Simon has been throwing well, no problem with using him. But, why not stay with the sharp pitcher on the mound, one who is already in the game?