Last time the 10year was at 2%, in May, TMV was trading around 70. Now that the 10 year is back near 2%, TMW is trading around 59.
That is the problem with holding this ETF for the long term. One would lose 15% since May.
It is very difficult to find a trading vehicle to short i rates. I have done everything from opening a futures account (MF Global issue with that) to writing options to try and create an instrument. Sometimes I just give up and buy gold or silver hoping for a correlation. The decay you mention is real and a problem since timing is near impossible but the major trend -- easy.