I started the year with 784k+ tier points (=mlife pts), played the weekend of 1/20-23 at Mandalay Bay and Bellagio and ended with 825k+ pts. I just checked my acct and it shows 744k+--why the sudden decrease. I got shuttled around to a few agents until I spoke to someone who knew: as you earn points they roll off the acct after 12 months, so even though the mlife system just started the tier points total actually is cumulative for 12 months back. Status In MLIFE, once earned, is good for 1 year from that date.
[In Harrahs system you retain status (once earned) until March of the following year--but on 1/1 of each year your base points get reset to 0].
PS: That I had to speak with several agents before I got an answer signals (to me) that they did not plan the MLIFE system too well.