With Alabama and LSU rated so close, only 0.121 ratings points apart, it is useful to look more closely, and what better way the my computer's performance charts and they appear below.
LSU has played a slightly tougher schedule, an average of 73.901 vs Alabama's 71.089, due mostly to playing Oregon in the first game of the year. Playing tough opponents is also a more meaningful game according my my algorithm and that is reflected by the green dot being larger.
Each team has been pretty consistent recently, especially the last 3 games each game rating being very close to the current rating, but each of those games not being terribly meaningful as they were against middle of the road opponents.
Alabama has also played a few weaker opponents in Kent State and North Texas, so perhaps LSU has been tested slightly more, but they play in Alabama so the computer is currently picking Alabama to win the game and finish the regular season undefeated.