Mitchell played for Saints for the first half of 2003 and was pretty non existent in midfield. The same can be said of Burns, who was with us for the second half of 2001. After scoring on his debut, he did sod all else until moving to Partick Thistle in early 2002, whom he scored a shedload of goals for in the SPL when played as a forward. In fairness to Toastie, however, he was played in defensive midfield by Tom Hendrie, who would no doubt have played Ronaldinho there had the loan signing come off!
Walker was with Saints the last time they won the league in 2000, scoring a few goals, including a great goal against Morton at Cappielow, and was a vital part of the defence. He was with Saints for three years before moving to Dunfermline, although did play for us as a trialist (against Brechin!) in 2003.
It would seem that Burns and Mitchell have been released because they aren't that great, whilst Walker has been transfer listed due to his high wages.
Meanwhile, one former Saint looks to be staying at Glebe Park, as goalkeeper John Hillcoat has been offered a new deal.
Story source: The Official Brechin City Website