I agree that cricket is a challenging game and analogous to baseball in many respects. But the batsman has twice as much time to swing versus a baseball swing based on average speed of the ball thrown in each sport. And the speedsThe only direct comparison to baseball (well not direct, but the closest viable one) is cricket.
The speed is similar (top level bowlers reach speeds of 90-100mph), but the key difference is that the ball typically hits the ground first, this lowers the speed (normally), but introduces another random variable as it can shoot off, on an unexpected trajectory, so no idea which is harder there, probably subjective.
As for the fielding, this isn't even close, cricket wins this hands down as fielders have to catch a similarly sized ball, similar hardness, hit at similar speeds...but they don't have the luxury of a huge glove!
As for pure Athleticism, definitely historically baseball wins over cricket hands down, but with the increased professionalism and introduction of T20 cricket I'm not so sure anymore, that again is subjective, especially as cricket doesn't allow substitutions (the only exception is for concussion if you're batting or for a fielder, but they then aren't allowed to bowl).
I'm not sure its clear cut though, hockey looks pretty tough (physically and the level of difficulty), some of the Gaelic sports (e.g. Hurling) look brutal and F1 / Indy / Nascar must require super human reactions (and higher fitness levels than people assume), so they could be up there too!
being attained in baseball that exceed 100 mph exit velocity are common and over 115 mph is no longer rare and with home run distances over 450 ft. Every MLB seems to have at least one pitcher that can throw at 100 mph or so it seems and 95-96 mph has become ho-hum pitches. And MLB keeps messing with the baseball all the time too like
this year in particular. Cricket is a assuredly difficult and popular but for speed and athleticism, baseball is number one.