While I consider myself an avid baseball fan, I've never followed the stats particularly closely. Most of my judgements of players come from what I've personally seen (TV or live) or heard (radio). So basically, I haven't much notion of the top prospects other than what's been written by secondhand sources. Unfortunately, they all use some strange stats to judge their ability.
One stat I saw on fangraphs that was used to suggest Runzler and Bumgarner (both of whom appeared solid as hell from when I've watched them pitch) aren't all they are cracked up to be is FIP. I looked it up and found this formula:
Fielding Independent Pitching, a measure of all those things for which a pitcher is specifically responsible. The formula is (HR*13+(BB+HBP-IBB)*3-K*2)/IP, plus a league-specific factor (usually around 3.2) to round out the number to an equivalent ERA number. FIP helps you understand how well a pitcher pitched, regardless of how well his fielders fielded. FIP was invented by Tangotiger.
To me, what with all the random integer multipliers, this stat seems arbitrary when compared to ERA. Does anyone here want to venture an explanation of how it is useful, or perhaps a more in depth explanation of the formula used to derive it?
I'd also like to open the discussion up to any stat you find particularly useful for judging hitters/pitchers that's more obscure than the classic BA/OBP/SLG or ERA. A personal favorite of mine is IP/GS for starters. It's a good indication of how much value you get from them per game.
If anyone mentions OPS they can go to hell. It's severely lazy.