Yes, the breadth of skillset is the issue. The real "old player skills" also includes low batting average. Dunn used to be able to run a little, but now he's very slow, and all it takes is a little drop in bat speed for players like this to fall fast, since they will see more fastballs since they aren't able to hit them as consistently, or as well. His contact rate is already slipping, too. Guys that rely on one or two things to get by become useless fast. Like Rob Deer or Richie Sexson did, for a couple examples. Dunn is a better hitter than those guys, but they are just examples.