Golden Age

Imagine if the top five players in the league in slugging looked like this:

You’d say that’s a league with some young talent. In fact, that’s the American League slugging leaders in 1909, just with the slugging averages adjusted from 1909 terms (league slugging: .309) to 2004 terms (AL slugging: .433). The players: Ty Cobb, Sam Crawford (this was the last year before Cobb and Crawford switched between center and right), Eddie Collins, Frank “Home Run” Baker, and Tris Speaker, all on their way to Cooperstown.
If you were going to pick a time and place in history to be a baseball fan, you’d be hard pressed indeed to pick better than the early teens, especially the American League. Just focusing on the young talent bubbling up, look at the young players coming into their own by 1911, many of them on their way to long and successful careers, including a bevy of inner-circle Hall of Famers. First the AL, ranked by age and Win Shares:

Bear in mind, this was an 8-team league. Even accounting for the tendency to have younger players in those days, this is something else, as evidenced by how many of these guys were still going a decade or more later. Then the NL:

* – Giants and Reds
You can see the seeds here for why the AL came to totally dominate the decade, winning all the World Serieses between 1910 and 1920 except for the 1914 “miracle” and the 1919 fix – the NL had a more normal age distribution, a few less immortals, and a lot of the talent concentrated on the Giants. (Also, a lot of guys named “Fred”). Presumably the difference was that the AL, having started in 1901, had less top-flight older players by 1908-09, and thus AL franchises were hungrier than, say, the Cubs or the Pirates.
At the opposite end of the spectrum, the Braves had Cy Young playing out the string at age 44 (2 WS). A good time to be picking young players to follow for years to come. Of course, the league was still segregated, and the rise of the Negro Leagues in subsequent years would begin to show how much fans of the majors were missing. And the problems already bubbling under the surface would emerge later – the gambling scandals, the salary squabbles that drove the Federal League revolt, the war in Europe that would eventually call a number of these players to service. But the early teens hadn’t been marred by that yet. A great time for baseball.
(Steve Treder has more thoughts on the era here)