The thing about GMs, is that practically EVERY fanbase thinks their GM sucks... until they win the Superbowl.
Case Study: Ted Thompson
Ted Thompson was a reviled figure in Green Bay in the days leading into Favre's retirement, and the circus that ensued. He continued to be reviled, and fans made case after case of his futility, until the Packers squeeked into the Playoffs at 10-6 and rode that to a Superbowl victory.
Just browse through this petition (that was made before their Superbowl victory) for some true gems from "knowledgeable" fans:
http://www.thepetitionsite.com/1/FIRE-TED-THOMPSON/
The same can be said of many more GMs throughout the league.
Jerry Reese (2 time Superbowl winner) -
http://articles.nydailynews.com/2011-09-14/sports/30173659_1_kevin-boss-jake-ballard-shaun-o-hara
Mike Tannenbaum - Once toast of the town in NY after back-to-back AFC Championship games, now has attained "Fireland" status from the fanbase:
http://turnonthejets.com/2012/11/tannenbaum-new-york-jets-nfl-tebow/
Scott Pioli - Remember the GENIUS who put together the Patriots Dynasty? Ya, he is getting run out of KC after a horrendous tenure.
The fact is, there is SO much that goes into the performance of a GM. A lot of that goes unseen until the perfect storm conspires to bring the team on a run. IMO, a lot is determined on the coaching staff's ability to develop the drafted players, and the QB to elevate the play of all the players on the team and mask the deficiencies. That is why Pioli (and Belichick) looked like genius in NE, but looks like an oaf in KC.
Is Ireland great? No, but he has shown to be at least middle-of-the-road to adequate, like the vast majority of GMs in the league. That "adequate" talent acquisition could turn into a Superbowl winner if the right circumstances come into a play and you have that one ingredient to make it all work. In most cases, that ingredient is superior QB play.
If Ireland is run out of town, could we get a GM that brings in better talent than him? Yes, but the odds are that the next GM will perform similarly to Ireland, or possibly even worse.
I don't know if it is worth risking, and honestly, I don't care at this point. Ireland has had many failures, with some successes. While this far exceeds the handful of GMs that preceded him here in Miami, it obviously hasn't been good enough to return us to the playoffs. That being said, there is a possibility that Tannehill is that missing ingredient who could make all his moves look like magic ala Ted Thompson.