The Lonnie Walker situation was pretty simple. Having him on the team on a guaranteed contract to start the season would cost the C's something like 11 million extra dollars in salary+ taxes. They weren't going to pay that for an end of bench guy.
Its not a Springer vs Wlaker situation. Springer is under a 4.5 million dollar guaranteed deal, to get off his money he'd have to be traded. Meanwhile Walker could just be cut. It's unfortunate because Lonnie flashed, but he was a tax casualty.