god as a cricket fan i feel sorry for Tendulkar, i am not sure if we can say if he has lost it but if you look at his performances in tests & ODI's since 2002 he has been very inconsistent in test while being superb in ODI's:
Off my head:
2002: Tests: Starting from the tests in WI when Pedro Collins had him all sorts of trouble during the tests, he came over here & had an inconsistent test series i only remember that 186 he scored in one of the test. He was home to the WI & i remember him scoring a match-saving 170 odd in Kolkatta, but overall don't think he was that consistent.
ODI's: During the natwest series and the ODI in the caribbean he did fairly well & the CT in SRI, while he didn't play in the 7 ODI's vs WI.
2003, Tests: failed their along with most of the Indian bastmen except Sehwag
ODI, cant remember what happened but i'm guessing he didn't do much because i cant remember
NZ came to India and i remember watching him score a boring 50 in Mohali & he went to Australia & failed pretty scoring that un-sachin like double in Sydney.
ODI's: Was superb in the WC, Superb during the TVS Cup.
2004, Tests: Incositent tour of Pakistan only that 194 in Multan, then he had that shoulder injury which messed him up when Australia were their, then he made his highest test score in Bangladesh
2004, ODI's: Had a decent VB series, did faily well in the ODI's in PAK, had a good Asia cup, i think he did well in the ODI's vs BAN but that irrelevant to an extent.
2005, Tests: Had a fair test series vs Pakistan, didn't do much when SA came to India, did fairly well in the test vs SRI i remember watching part of his innings in Chennai when he was hitting Mural & Vaas around.
2005, ODI's: Incosistent in the ODI i remember him scoring just a century as his only significant score, had a very good OD series vs SRI, but followed that up with a poor one vs SA.
2006, Test: Average test series vs PAK, poor vs ENG so far
2006, ODI's: Pretty good vs PAK
So we can see that he has really declined in his consistency has a batsman since 2002 in test while his ODI has still remained very good. So i dont know if he has really lost it totally but i dont think we will ever see the Sachin of before, especially the one that was so destructive vs Australia in 98 (now that was vintage Tendulkar word out).