LOS ANGELES – Indianapolis Colts quarterback Andrew Luck announced his retirement Saturday night, sending the NFL world into shock. In other news, the Broncos continued their slough through the preseason with a 10-6 loss to the Los Angeles Rams. None of the Broncos’ projected Week 1 starters played. The Broncos’ offense consisted of two Brandon McManus field goals. The Rams took the lead for good on fourth-team quarterback John Wolford’s four-yard touchdown pass to receiver Jalen Greene. The Broncos mercifully close the preseason at home Thursday against the Arizona Cardinals (7 p.m.). “I think (Saturday) will be very valuable (for evaluating the roster) because our practices were limited last week,” coach Vic Fangio said.