My guess would be some kind of commercial obligation with new sponsors? The OS article states that the players going to Ireland wil be "the remainder of the first-team squad", thus implying that the team going to Macau is also a first team line up. That said, there is a fair amount of overlap between our U23 squad and the first team squad so maybe a mixture of the two. I can't imagine Hasenhuttl being overly happy with breaking up the squad during pre-season though...