Are You Really Seeing What You Think You Are Seeing?
When you are studying a baseball player, or really anything else in life, always ask yourself: am I really seeing what I think I'm seeing? Or am I seeing what I expect to see, with said expectation perhaps not being what is really there?
Here is a non-baseball example that might illustrate this principle in a fresh way.
The Heinkel 100 was an experimental high-speed aircraft developed by Nazi Germany in the late 1930s.
It pushed the technology envelope at the time and had some teething troubles, but after the bugs were worked out, it was an amazing aircraft and set a world speed record in March of 1939.
The Heinkel company built some additional pre-production prototypes, developing the airframe into a potentially outstanding fighter. The 100 was faster than the contemporary and much more famous Messerschmidt Bf 109. The 100 also had twice the range of the 109, and was just as maneuverable. It might have been the best fighter in the world until the debut of the North American P-51 Mustang.
Despite these advantages, the Heinkel 100 was never placed in production, the Luftwaffe preferring to concentrate on the Bf 109 for political and economic reasons. Certainly the Messerschmidt was an excellent (if tricky) aircraft, but the Heinkel was even better.
This was a good thing for the world: if German pilots had been flying the He 100 instead of the Bf 109 in the Battle of Britain, the outcome might have been different.
In any event, the Germans did find use for the 19 prototype 100s that had been built. Nazi Propaganda minister Joseph Goebbels had a series of magazine articles written, complete with glossy photos, about the "new Heinkel 113" fighter, said to be devastating the Allies.
There was no such thing as the Heinkel 113: the photos that accompanied the articles were photos of the prototype 100s painted and re-painted as different aircraft, to give the impression that hundreds of 113s were in service.
Despite the fact that the 113 never existed, and that the small group of 19 Heinkel 100 prototypes were never operationally deployed, Allied pilots reported encountering and shooting down 113s in combat for several years.
These encounters were really with Bf 109s, but Allied pilots expected to see 113s, so they saw them.
They reported what they thought they saw, which was what they expected to see, which (in this case) wasn't real. In the heat of combat such mis-identifications are understandable, but it serves to illustrate the principle that even "eyewitness" accounts can be unreliable, that our eyes can deceive us.
So when analyzing a prospect, with scout/visual methods or sabermetrically, it is always a good idea to step back and think. Do I like (or dislike) this guy because I'm expecting to?