Each iteration of a sports title comes out with something a little different than the last. This is just good marketing strategy, because who would want to buy the same game twice? MLB 2004
has a nice batting and pitching system, as well as good control for your field players. The pitcher chooses a pitch and selects where he wants to put it over the plate. The batter gets a quick glance at where the ball is coming and then tries to position himself for a hit. This works rather well, as does the pitch/guess ability that allows the batter to guess where the ball is coming, and if he is correct, his chances of a good hit increase dramatically.
The problems with control arise on both sides of the coin when people are running the bases. Controlling the runners is confusing as hell, and they always seem to take their sweet time to leave the base. The problem for the fielders is that the 'sprint' button is the same as the button to throw to first base. When you sprint to pick up a ball, if you don't let go right before you get there, you'll always throw to first base, which leaves the guy heading for home safe and sound.
Despite the tricky controls, dated graphics, and a few bugs, MLB 2004 is actually a decent baseball game. For PS One owners, this is the baseball game to buy. And if you're a baseball fan, then you should get out and buy it right now. However, sim haters may find it boring and repetitive (a large complaint of real baseball these days). Only baseball lovers need apply here.