If a farm system "produces" 7 players for the 2010 team there's a lot of value in that, even if those 7 players are SP #3,4,5 Relievers #5,6, and Bench Players #24,25. (The end of the rotation, bullpen, and bench.)
There's value in the minor league system producing that because you don't have to go out and spend on free agents to fill out a competent roster.
But I think we get wrapped up in what one prospect is doing from year to year, see that Todd Frazier is tearing up AA, Devin Mesarosco is smoking Single A and Travis Wood is untouched in AA. When those guys hit a wall, we blame it on the the farm system. Say it's holding back players. When the odds that Devin Mesarosco ever plays for the Reds, much less starts for them are pretty remote.
My guess is there is not a single farm system in Baseball that could have screwed up Albert Pujols, it wouldn't have hurt Mike Leake to go to AAA, but he was able to come straight to the majors. There's no development in those players. Likewise, you can't hold the development side responsible when you're not producing guys like that.
If we exclude Leake from the discussion on those grounds,
From the development period TRF mentioned earlier, the farm system has "produced;" a starting GG caliber CF with an above average OPS for the position, a starting GG caliber RF with an above average OPS, A major league quality backup outfielder, One major league quality backup infielder, One Roughly League Average Starting Pitcher(Cueto:99 ERA+) One Below Average Starting Pitcher(Lecure and Bailey Combined: 82 ERA), and 3 replacement level relief pitchers.
Essentially that's 11 players and 9 slots on the 25 man roster at any given time on a team that is currently 7 games over .500.
To me that sounds like a pretty good haul and doesn't even consider the development of players acquired previous to 2004, like Votto and Hanigan, the development of players like Stewart and Roenicke who were traded for a key player on the 2010 team. It also doesn't consider guys like Herrera or Masset who have spent some time in the minors but came from other organizations.