Rookie Pitchers in the American League

Earlier this week Baseball Nation’s Rob Neyer noted that the Oakland A’s are currently starting five rookie pitchers in their rotation. While Neyer opted not to make any analysis of the situation, we decided to take a closer look at those rookie pitchers. In fact, we decided to look at the impact of all rookie pitchers on the playoff race, to see if we could learn anything that might benefit teams in the future or predict the outcome of the current playoff race.

Here are a couple basic ground rules before we got started:

1. All pitchers are eligible if they meet MLB’s rookie guidelines. This includes players like Yu Darvish who played top-level international baseball and Travis Blackley, who has played in parts of a couple of seasons.
2. We included all the teams currently still alive in the playoff race.
3. We limited our scope to the last 28 days, mainly because that is how the folks over at Baseball Reference do their splits.

After grinding through the numbers and eligibility we were able to make a few observations, if not draw concrete conclusions about the use of rookie pitchers for contending teams.

• The A’s and Orioles, this season’s surprise teams, had the most innings pitched by rookies.
• Five teams, the Yankees, Rangers, A’s, White Sox and Angels, had a better rookie ERA than overall team ERA. And the Orioles were virtually even.
• The Rays were the only team significantly hurt by rookie pitchers, with an ERA almost 4 runs higher than the team average.
• The White Sox have the worst record at 10-15, but their rookies gave up over 2 runs fewer per game than the team average.
• The Orioles have played 21 more innings during that period than any other team.
• The A’s rookies, at 10-5, had a better record than their veteran counterparts at 5-5.
• The highest payroll teams, the Yankees, Angels and Tigers, used rookie pitchers the least.
• There was no relationship between rookie usage and record.

While the results aren’t definitive (it would take a multi-year assessment to determine if these statistics are a trend) it does appear that using young pitchers does benefit teams overall. We’ve included a full breakdown of each team’s utilization and results below.