Big deal if they had already qualified - Madrid were already through - they only won a moderate 4-0 - No excuse - at home infront of your own fans you must win - These are professional sportsmen who never play to lose
When did you start watching Italian football?
Milan have been doing this for ages. Take a look:
2010/11 - They didn't need any points in the last round ---- lost 0:2 to Ajax in Milano
2009/10 - Didn't need pts because Real was beating Marseille in the last round ----- 1:1 with Zurich in Zurich
2008/09 - didn't play CL
2007/08- Needed a win to secure the 1st place --- 4:1 against Shakhtar
2006/07- Had the 1st place already secured ---- lost 0:1 to Lille in Milano --- won CL in the end.
2005/06 - Had to win ---- 3:2 against Schalke
2004/05 - Needed a point to secure 1st place ---- 0:0 against Celtic
2003/04 - Had the 1st place secured ---- lost 1:2 to Celta in Milano.
If I go further back you'll get the same results. This was the 3rd time in the last 7 years for Milan in Europe when they didn't need any points at all in the last round and they lost the match (at home, even more).
Milan and the Italian teams in general never ever play to win or even draw if they don't need the points. This attitude partly contributes to losing a CL spot.