BATON ROUGE, La. — With its back against the wall, Alabama delivered on a massive stage. The 11th-ranked Crimson Tide went on the road to Death Valley, and not only emerged victorious over No. 15 LSU, but did so emphatically. The 42-13 win moved Alabama to 7-2 on the season, with a 4-2 mark in SEC play. More importantly, the win kept the Crimson Tide from picking up its third loss of the season, vaulting it right back into the thick of both SEC title and College Football Playoff discussions after another wild Saturday. Alabama quarterback Jalen Milroe needed to have a big game, and he did just…