Ortiz was a first baseman for both Minnesota and Boston. Eventually, with age, he was relegated, and rightfully so, to DH.
Montero, as a young stud was never groomed into a position. What does that say for your developmental acumen that you can't even teach A KID a position. Ortiz was a later age changeover and correct me if im wrong but Napoli played multiple years as catcher.
Ortiz is a DH who owns a 1B glove. He is not a 1B. His high water mark for games played at 1B was 75 and that was his first year at age 22. Since then, he rarely plays the field.
Napoli has rotated between DH, C, and 1B, but he's never caught more than 96 games in a season (that was in 2009) and his 1B numbers suggest that he shouldn't be playing there regularly.
Did the Twins, Red Sox, and Angels fail to "groom" Ortiz and Napoli to play a position? Or could it be that they have major league bats but not major league gloves? Everyone has their limitations.