Granlund is a pending UFA who was very unlikely to re-sign with the Sharks. He's already 32 and will probably try to find a spot in a contender. He was part of the return/cap dump for Karlsson and after being a good contributor he's now a late 1st rounder for the Sharks.
Grier is being the opposite of dumb. He took a player that was underperforming as part of the Karlsson cap dumb, who then became a valuable contributor, then shipped him before his contract expired and now Grier has yet another good future asset.
The Sharks should absolutely not be retaining aging veterans for the long haul. Until their young guns can start pushing the team into the playoffs, they should be bringing in players who are still fighting to improve their game or at least keeping themselves from declining. The Sharks would've needed to give Granlund a retirement contract for him to stay and he absolutely would not have the impact he had earlier with a deal taking him to his late 30's on a team still years from Cup contention.
See how the Hawks still suck so much - overloading the roster with mediocre 30 y/os and declining veterans on multiyear deals who wouldn't have gotten a better deal anywhere else. You want to bring in people who want to compete with the young stars and push them to do better, not just be voices of wisdom who know they aren't fighting for shit and are looking forward to an early vacation while the young stars' development stall.