What does age start? You look at every other factor and where that person fits on a generic age curve gets thrown out. Parmelee could OPS and play the field pretty much how he has been playing until he is 40. It is not going to happen. If his level of play doesn't improve, he will be out of the league by 30 because there will be somebody cheaper with more upside come along or they were not very good in the first place and got their shot.. From the last few years Twins alone Johnson, Darnell, Thompson Achter, Mastroiani, Nunez, Fryer, Hermann, Florimon, Thomas, Ramirex, Diaomond, Pedro Hernandez, Martis, Tyler Robertson, Albers, Walters, Komatsu, Nisihioka, Luke Hughes, DeVries, Matt Maloney, Manhip, Waldrop, Vasquez, Grey, Burnett, and Perdoma are all highly unlikely to be in a major league uniform when they are 31. They all count against that age curve. You would be hard pressed to say they were out of the league because their skills declined with age. Their skills did not develop further to keep them on a roster. Valencia, Alexi Casilla, Hicks, Pinto, Shaffer, Parmelee and Escobar could all fit that model.