Earlier this week I received the following trade offer from a fellow NL-only league owner:
"Hey Kevin: Would you be interested in a Zach Duke for Wily Mo Pena deal? Duke is at $1. In the last 16 1/3 innings, he's allowed only 5 runs. His ERA would be even more impressive if the idiot Pirates manager didn't leave him in to start the 8th inning Tuesday night with a 12-1 lead. His reliever gave up two of the baserunners he inherited. This is the best Duke has looked since 2005 when he was 8-2 with a 1.81 ERA. I have pitching to deal and am willing to gamble."
I have never had much interest in Zack Duke but because I am desperate for pitching I considered the offer. To evaluate the trade I did not use the statistics my fellow owner included in his offer. Despite the fact ERA is a standard scoring catagory in fantasy leagues, it is not a good way to evaluate a pitcher's performance. Even though Duke has only allowed 5 earned runs in his last 16+ innings of work I quickly discovered he isn't pitching any better now than he has in the last several seasons.
Zack Duke has pitched 20.1 innings in his last three starts. In those three starts he struck out 6 and walked 7. There is no way a starting pitcher that walks more hitters than he strikes out is going to help a fantasy team. Duke's .86 strikeout to walk ratio is well below the National League average of 1.84. Duke's 2.66 strikeouts per 9 innings ratio is more than 4 strikeouts below the National League average of 6.68. It was easy to correctly determine Zack Duke is a very below average National League pitcher. As desperate for pitching as I am, no way am I making a deal for him.
When evaluating a trade for a starting pitcher I rarely look at the pitcher's ERA. Instead I consider the pitcher's strikeout to walk ratio (K/BB), strikeouts and walks per nine innings pitched (K/9, BB/9), and batting average of balls in play (BABIP). I then compare these ratios with league average. If the pitcher is league average or better, I consider making the trade. This is a simple way to determine the quality of a starting pitcher.
If you receive a trade offer for a pitcher with a low or improving ERA dig deeper into the statistics before saying yes. More than any other statistic, a pitcher's ERA is a product of good or bad luck. Failure to take the time to examine how the pitcher is truly performing could result in you being stuck with an ineffective starter that every five days hurts your team.