Can understand his move - for his career. People downplay the SPL but I would rather hang up my boots having played 10 years in the SPL than L2 and a foray into L1 in England. He'll have the chance (albeit slim) to win a League title, play in Europa League, be seen by more scouts and maybe get a better move in the future to a higher profile SPL or English team.
Similar perspective, I guess like us, many clubs send scouts to Scotland to find "wee nuggets" maybe he feels he will get more exposure there than he would playing for Argyle in L2?
Whilst I don't lament the club for announcing it if it was really that nailed on - we have been stung for sure. Shambles, I don't think so - some of the criticism of the club around this has been unwarranted IMHO.
Will he be a loss, depends which CM turned up this year. Maybe there is a better DCM out there who can fill his position and help us push forward and wants to play for Argyle. DA would definitely have alternatives lined up, albeit we have missed a week or two he will have targets in mind as he would have to plan for CM jumping ship.