I did when I saw Sam's apparent age and his voice change, but after seeing his sonar goggles and the uttering of FOURTH ECHELON :question: I was suspended in disbelief.
Wasn't Sam a Navy SEAL? Didn't he have an illustrious past of covert assignments? Why can't we go into that? Then at least his new appearance would make sense, and we could possibly have a more classic splinter cell with the technology gap. Like doing the Chaos Theory mission in wartorn Seoul, except instead of Souel you have Baghdad or Kuwait City.
Sam even fought the Soviets in their invasion of Afghanistan, operated behind the Iron Curtain, the invasion of Panama, fought arms dealers in Africa... the list goes on.