The boys are practicing baseball catches in the back yard while Mike finishes his blueprints for the future residence of Don Drysdale (big name in baseball). Don is impressed, and Mike asks Don to meet his boys. The boys are thrilled, of course, and Don gives them some baseball pointers. Don reckons Greg will be in the big league one day, and Greg starts having big dreams about being a big baseball player. It starts turning into an obsession, with Greg going as far as staying up in the middle of the night with his workouts. The parents and Alice are not pleased to be woken up over this. After Greg finds out what bonuses baseball players, he gets even more obsessed, swotting up big baseball dates and not doing his homework. Carol is deeply concerned, but Mike thinks it is fairly normal, as most American boys dream of the big league.
Then one of Greg's teachers, Mrs Pearson calls, to say Greg's grades are slipping (they are usually good), he keeps giving baseball-based dates in his history class, and did not turn in his history assignment. When confronted, Greg tells his parents he did not have time for the assignment as he regarded his baseball dates as more important. Believing he has a career in baseball, he sees no need for high school or college. The parents wonder if Greg is threatening to drop out, and this starts an epidemic when Bobby and Peter ask if they need to finish their schools as well. After this, the parents definitely have another word with Greg, but all Greg can think of is baseball.
Mike goes to Don, feeling Don is the only one Greg might listen to. Don is upset as he only meant to encourage Greg, and agrees to try to make Greg see that baseball is not everything. He starts a conversation with Mike within Greg's earshot about some of the shortcomings of baseball, especially for players who do not end up in the big leagues. But this only makes Greg even more determined to make it to the big leagues. The parents fear Greg is heading for a fall and they will have to pick up the pieces.
Greg has a big game is scheduled for Saturday. He comes home early and extremely upset. He was so cocky that he would not listen to the coach. He ended up being clobbered so badly that the coach pulled him out. He finally got the fall his parents feared was coming, and now it is time for Mike to pick up the pieces. Greg has lost his obsession with baseball, but is so upset that he wants to quit the game altogether. Mike tells Greg that he is now going the other way. Eventually he persuades Greg to get back into baseball, but in more moderation. Just be the best player he can be, and remember that there are other parts of life.