Colombo signed with the Cowboys during the 2005 season and remained with them through the 2010 season. Previously, Colombo played with the Chicago Bears - who had made him a first round draft selection in the 2002 draft.
Sparano was the offensive line coach in Dallas from 2003-07, spending a few years with Colombo. Of all the places for Colombo to sign as a backup/spell type of player, Miami makes a great deal of sense just for this reason.
Colombo's release also fits in with Dallas' plan that they began in April with the selection of Tyron Smith: the rebuilding of the offensive line. Colombo had been a familiar face for quite some while, but turnover is necessary if Dallas is truly looking to rebuild and reload on the line.