Solving Instant Replay and Saving Time

Here is the solution.

Each manager gets one incorrect challenge per game. The manager can challenge any call he wants, and the umps will go into the booth to look at it. If the manager is right, he still has a challenge in his pocket.

The manager's challenge can be invoked in two ways: 1) A "red flag" (like in football) is thrown out on to the field, or 2) the manager comes out of the dugout to question any judgment call, in which case the replay is immediately invoked.

There could also still be umpire driven replays on boundary calls (like there are now).

This would not slow the game down, as managers would not waste their challenge on an unimportant (or too-close-t0-call) call. Moreover, it would actually speed the game up, because managers would not come out of the dugout to argue every little thing, as he would risk the umpire raising his hand (or whatever) to indicate that the challenge had been invoked.

Also, unlike football, these decisions would be made instantaneously, because there would be no review after the next pitch, or, at the end of an inning, when the defensive team has left the field.

Problem solved. Next question?