Remember with AF447 the search team had a good idea where the aircraft crashed, and had found substantial amount of debris (including two male bodies) just 5 days after the crash.
Even so it took them another 2 years to finally find the main fuselage of AF447.
On the other hand, the flaperon may have drifted for over a year before reaching Reunion. It's unrealistic to think anyone can track back the location of MH370 with any kind of accuracy, based only on general oceanic drift patterns.