Joe Philbin had real concerns that J-mart had sufficient strength and skills to adequately protect Tannehill at Left Tackle. The basis of a deal with KC to recruit Branden Albert was in place but Ireland wanted to show himself as a top negotiator and didn't pull the trigger. J-mart at Left Tackle was probably his backup option but that's what he was left with. Jeff loved the negotiating and fancied himself as a good negotiator.
Ireland's failure to get the O-line talent from numerous expensive Free Agent and high Draft pick investments, is a big reason for his departure. But the other reason is that the Head Coach and GM have to be on the same page and working together. It is possible to interpret Ireland's actions as being disruptive. Leaving J-mart as the sole LT hope was Ireland's big gamble that ultimately failed badly. Joe flagged his dissatisfaction after a loss and McKinnie was traded for the next day.
It's all water under the bridge now, but I think Southbeach is right in that much was preventable if Ireland had just completed the deal with KC and brought in Albert. The deal was on the table.
The only good coming from this is that Ireland, Sherman, Turner, Incognito and J-mart have all left the building.