it could be used for any one of a variety of reasons. doesn't like the manager, the Cubs aren't winning, his mistresses are hiding around doorways with weapons, the crowds are on him or he thinks he's not getting full market value whether he is or not. he can strong arm all he wants, the Cubs don't have to sign a 33 y.o. player to a 5 year contract if they don't want to. he can opt out and the parties can part ways. the way I understand it is at the end of four years, Aramis can decide if he wants to opt out. if he does, the Cubs can let an aging slugger walk or resign him. if he decides not to opt out, then the Cubs then have a regular team option. so he can strong arm all he wants, the Cubs don't have to sign a 33 y.o. player to a 5 year contract if they don't want to. he can opt out and the parties can go to arbitration or part ways. the only way he can hold the Cubs over a barrel is a terrible market for thirdbasemen in 4 years, no viable prospect or filler, and the Cubs are trying to remain competetive. nobody knows what the market for thirdbasemen will be in 4 years or if the Cubs will be trying to remain competetive. The point is the Cubs would have to make a tough choice in that situation because it'd indicate he's playing well. On the other hand if he's not then he won't exercise it. That said, if it saved the Cubs 30m by giving it then it makes sense however overall the opt out is a bad thing for the Cubs.