There are many ANers who post often asking about good places to go for info.
For my money, David Pinto's blog, baseballmusings.com, is simply unmatched.
Pinto couldn't have better qualifications/credentials as a blogger: He's worked for STATS, he's worked for ESPN, and he created his own outstanding model for evaluating defense - the probalistic model of range.
I study baseball quite a bit, and I value what Pinto has to say about defense over Dewan, James, or any other model I've heard or read about.
During the day, Pinto is following all the major league baseball action and posting outstanding brief entries on all the big league action. He continually makes insights and connections that aren't being written anywhere else.
*Today he pointed out Grady Sizemore's incredible run-scoring pace, and the fact that Rickey Henderson is the only player in the last 50 years to have more runs scored than games played (minimum 100 games). Pinto logically points out that given Sizemore's speed, power, terrific offense, and position in the order all give him a legitimate shot to challenge that mark.
*He has a terrific graph pointing to the average age of Major League hitters, and concludes that "batting age" is at its highest since WWII. The average batting age in 2007 is 29.6 years - probably past a hitter's peak. Is that a small factor in why offense is down? Is it indicative of teams rewarding past experience rather than FUTURE performance in free agency and not giving their young players a chance? (Think of the Dodgers blocking their young guys with Gonzalez and Pierre, or the Giants signing Roberts rather than giving Linden a chance).
*Pinto also points out that one of the main stories of the young season is the decline of offense thus far. Through a week and a half, there had been 140 - 140! - less homers hit league-wide vs. the same amount of games last year. Yes, its a small sample size and the weather was cold...but it was also cold last April, and that probably can't alone account for an average of 1 less homer per game. Run scoring overall was also down from 10.8 to 8.2 over the same time frame. Pinto very thoughtfully theorizes that offense may be down as a result of MLB quietly mandating that teams league-wide keep their game balls at 70 degrees this season, in response to Colorado successfully holding offense down through its use of the humidor the past few years.
These are relevant questions, and terrific data, and you don't find that on ESPN, but you will see that type of stuff at baseballmusings every day.
I've never met David Pinto and he doesn't solicit praise, I just think his blog is outstanding daily reading for the ANers who are passionate about learning more about baseball.
Other great resources are:
hardballtimes.com - free and updated five times per week with terrific statistical analysis and great writing
http://mlbcontracts.blogspot.com - Cot's Baseball Contracts - If you ever have a question about a guy's salary, how much service time he has, when he'll be a free agent, who the next season's free agents are, this is THE best source on the internet.
mlbtraderumors.com - His slogan is, "If it's whispered, we hear it." This guy runs an outstanding site, and he isn't even doing it full-time. He recently solicited an A's fan to be his source for all A's news, and if you go to site, you could still apply to do it. He links relevant news articles on all things MLB (not just trade rumors) throughout the day, up to the minute. He's like Ken Rosenthal without the awkward forced smile.
And the obvious ones -
baseball-reference.com - amazing statistical reference for any current or previous major leaguer; also has all MLB active- and career record holders.
thebaseballcube.com/minorleaguesplits.com - If you ever hear of a trade for a prospect, go here to analyze their numbers. As far as I can tell, this site has minor league and COLLEGE stats for practically everyone in an organization since 2001. Wow.
baseballprospectus.com - Much like ESPN Insider, a lot of people no longer think it's worth the fee given the proliferation of free info available on the internet. But BP offers an "Unfiltered" free article or post almost daily that is still very much worth reading.
**If anyone has any other sites that they think are excellent, preferably of the informative/non-ranting variety, please do post those as well. I'm always looking for great new sources of information.