Goku could follow the Tenshinhan's movements because his sensor of ki was far more advanced than 3 years ago.Mike said:Weighted Goku could still follow Tenshinhan with his eyes, so I doubt Tenshinhan's speed is that far above post-Water Goku. Popo on the other hand completely man handled Goku effortlessly.
There's no reason for 23rd TB Tenshinhan to be close to Popo. I don't see BoZ Tenshinhan winning either.