As the first replier indicated,  TIPs  (and I-bonds) returns are determined based on a cynical undercounting of price changes by the Govt.     Since 2000, our nation has experienced substantial price inflation in   housing, energy prices, food, and health care insurance.    These changes have simply NOT been accurately accounted for by the Govt, and so not reflected in the 'inflation protection' component of returns for TIPs.

Compare the performance of your favorite TIP  vehicle to "CEF"  an exchange traded fund which holds silver and gold bullion.     Or, go to the M* tool and compare VIPSX to PCRDX ,  a commodity index fund. The results should lay to the rest the efficacy of TIPs as an inflation hedge.

TIPs would be a wonderful vehicle if the govt told the truth about  (and paid you accordingly) inflation.  But they never will.   TIPs  DO provide inflation protection:  they protect the issuer (the U.S. Treasury) from paying real interest rates to savers/investors.