Then, too, there are the measuring devices and their dependability. Finally, the matter of definition of what is actually being measured can further muddy the waters.
1. Generationally, other sports reflect dramatic evolutions in training methods, equipment worn or used, strength routines that result in shattered old records, with the new one rarely lasting very long themseleves. This is especially so in individual competitions and "team" efforts that arise from individual competitions, like relays. Here the basic competition faced by the athlete is the clock. The skills and feats are awesome; but they are very narrowly and singularly focused, not calling for much in the way of adaptive challenges and other than rote activities and muscle-memorization routines.
2. Football, despite all the hoopla of Super Bowls and College Bowls and media income funding "higher education" at most institutions, has honed specialized skill sets in athletes, many of whom have sacrifced healthy middle age for a few years of highly payed success of the gridiron: obesity, adult onset diabetes, failed cartilege, joints and muscles, arthritis and rheumatism .... old age by 50. Are they bigger and faster???? Anyone remember 310# Big Daddy Lipscomb tracking running backs across the width of the field annd jarring them to a halt?
3. Basketball, most legitimately strartling of all has ingeniuosly destroyed the 50 year old sereotype of the clumsy, awkward "big geek" of 6'5" and above who was a potential asset so long as he didn't try to dribble the basketball. Some very savvy types saw the stereotype as a straw man and plugged into the Globetrotter~showmanship theme and devleoped the sport into a run and gun display of physical grace.
However, if refs called traveling, catching one's own pass, palming, three seconds and other violations with anywhere near the scrutiny of, say the 1950s's and a good percentage of baskets would be disallowed. Also, where the thrill arises from a 6'10" player dunking a ball escapes me completely.
4. Baseball, by comparison, has skill sets that must be adaptive to changing situations at every position; so the fad is less likely to work its way into the fabric of the game. Aluminum bats are not used for the simple reason that physics tells us somebody would soon be killed at the MLB level of competition.
5. Pitch velocity: What is really being measured; and what, on the other hand, do most fans and hitters and scouts want to be measured.
-The modern "guns" are individually callibrated [suspicious???] so their reliability depends on the callibration. These devices capture the forward speed of the pitched ball in the instant of release from the pitcher's hand. So, 103.2 mph is clocked at a distance somewhere around 58-59 feet from home plate. That 103.2 is not what the batter sees a fraction of a second later, when the pitched ball truly becomes a pitch, having entered the batter's contact zone. It has been tested time and again for air pressure, gravity and other forces, revealing that the pitched ball will lose 6-8-10 mph from that instant of release until entry into the swing zone of the batter. [To my knowledge, nobody has been clocked at 103.2 in the contact zone.
-gravity drop, Army artillery shell velocity devices and the like have tested pitchers from Walter Johnson to Bob Feller; and these seem to focus on feet-per second, where 144 ft/sec = 98.18 mph. If I understand these tests correctly, they capture average speed between point A and point B, which would be more satisfactory than a point-of-release snapshot the the hitter never really "sees" at the plate. The math above is simply 144'/sec * 60 [seconds] = 8,640' in one minute. We know that a mile a minute = 60 mph; so 8,640/5,280 = 1.636*60 mph = 98.18 mph.
-If this exercise brings us back to the gun, then a Zumaya fastball released at 103.5 mph might just enter the contact zone of the batter at 144'/sec or 98.18 mph, a loss of 5.32 mph from instant of release.
Bottom line, at least for me, pitchers from 1901 through 1970 could bring it at a release point spped of 100 mph, consistently entering the swing zone @ 92-98 mph. Because of game psychology of starters going deep into games, they paced themselves and didn't go all out on every pitch, preferring to mix speeds and ball movement.
Today's starters, in an age of higher specialization, do not face 9 inning games as a fact of life, so they may go more often with what they consider their $$$$$$$$ pitch. If it's the fastball, they'll throw it more often.