As my sig shows, I don't think he's done a great job at selecting talent (although a lot of people question who was making what picks.)
His best draft was 2016 and he only really got 3 players out of it, 1 of which he already flipped for more lottery tickets. It was also the only draft he got a pro bowl player out of. 2017 was horrid. 2018 looks pretty bad at the moment too because the one good player you got out of it was just traded for essentially a deferred lottery ticket at around the same position. Might just end up with a decent LB and a kicker out of that draft. 2019 way too early to tell, but at the moment only looks like Wilkins and Deiter have any kind of longterm future with the team. That isn't a great track record.
That being said, one thing I really do like about Grier's approach vs when Tannenbaum was leading the team is that he maximizes his opportunities with draft picks. T-bum would throw out picks like he was in the champagne room to the point he really only got around 5 selections. Grier is taking an approach similar to Jimmy Johnson.
I was looking at JJ's Dolphins drafts earlier:
https://www.pro-football-reference.com/play-index/draft-finder.cgi?request=1&year_min=1996&year_max=1999&draft_slot_min=1&draft_slot_max=500&pick_type=overall&team_id=mia&pos[]=qb&pos[]=rb&pos[]=wr&pos[]=te&pos[]=e&pos[]=t&pos[]=g&pos[]=c&pos[]=ol&pos[]=dt&pos[]=de&pos[]=dl&pos[]=ilb&pos[]=olb&pos[]=lb&pos[]=cb&pos[]=s&pos[]=db&pos[]=k&pos[]=p&conference=any&show=all&order_by=default#results::none
He came into every draft with a ton of draft capital. While he drafted a lot of stinkers, he always came away with at least 2 elite players who would go on to become the foundation of the team (specifically defense) which would carry them for almost a decade.
So even though Grier's drafts haven't set the world on fire, the approach may lead to a higher hit rate of elite players being drafted than we've seen in the past just due to the more tickets in the raffle we have. More tickets = more chances to win.
That being said, I really don't like the way Grier is approaching jettisoning proven young talent from recent drafts for more lottery tickets. Those players were supposed to be foundational pieces. We spent time and energy in developing them. They could have been seasoned when a QB gets here making the transition to playoff team easier and quicker. But now the entire timetable has been set back by essentially deferring those picks with another roll of the dice.
I hope, if we retain Grier, he uses this haul to flip for future picks to keep his annual draft haul rather large like JJ did.