Tyreke Evans, Stephen Curry & Brandon Jennings: Are They in a Sophomore Slump?

Reservoir GodCorrespondent IIJanuary 30, 2011

SACRAMENTO, CA - DECEMBER 06:  Tyreke Evans #13 of the Sacramento Kings in action during their game against the Miami Heat at ARCO Arena on December 6, 2009 in Sacramento, California.  NOTE TO USER: User expressly acknowledges and agrees that, by downloading and/or using this Photograph, user is consenting to the terms and conditions of the Getty Images License Agreement.  (Photo by Ezra Shaw/Getty Images)
Ezra Shaw/Getty Images

NBA.com ran the following story Thursday afternoon: "Evans, Curry, Jennings work through sophomore slumps".

According to the article, NBA coaches Paul Westphal (from the Kings) and Keith Smart (from the Warriors) think there is a sophomore jinx in the NBA:

"I guess people talk about the sophomore jinx for a reason,'' Westphal said.

"You're not a surprise anymore,'' Warriors coach Keith Smart said of the adjustments players face in their second season. "Especially a guard, very few of them have that great first year then a great second year. They may play consistent that second year, but not that great year. Some of them do. But a lot of them, they don't.''

I thought Smart's comments were surprising since David Berri and Martin Schmidt reported in the book Stumbling on Wins that the average NBA player improves every season until age 25. 

Berri and Schmidt used a statistical model called Wins Produced to measure players' productivity based on how much their box score statistics contributed to their team's efficiency differential and wins. An average player produces 0.100 wins per 48 minutes (WP48), a star player produces 0.200+ WP48 and a superstar produces 0.300+ WP48. More information on these stats can be found at the following links:

Simple Models of Player Performance
Wins Produced vs. Win Score
What Wins Produced Says and What It Does Not Say
Introducing PAWSmin — and a Defense of Box Score Statistics

Is the Wins Produced story different for Evans, Curry and Jennings? What does it say about rookie guards in general?

To answer those questions, I gathered a list of every rookie guard that was chosen with a lottery pick or received votes for the Rookie of the Year award from 2003 to 2010, and then gathered their Wins Produced stats from NerdNumbers.com.

The results were interesting.

Evans' Wins Produced per 48 minutes (WP48) has declined from 0.157 to 0.065, which was the third largest decline among guards that were either chosen in the lottery or received Rookie of the Year votes since 2003. The biggest declines were Jonny Flynn (-0.158 WP48 from 2010-2011) and Rashad McCants (-0.129 WP48 from 2006-2007).

The common theme among all three players was that they experienced significant injuries. Evans has struggled with plantar fasciitis this season, Flynn had hip surgery in the off-season and McCants had microfracture knee surgery after his rookie season.

Curry and Jennings have made slight improvements this season. Curry's WP48 slightly increased from 0.147 to 0.150 and Jennings' WP48 increased from 0.067 to 0.100.

Despite what Smart said about NBA guards, the improvements of Curry and Jennings were more the norm than the exception.

There were 48 rookie guards that were either chosen in the lottery or received votes for Rookie of the Year since 2003. The average rookie guard from that sample improved their WP48 from 0.081 to 0.113. Only 39 percent of the rookie guards in the sample performed worse in their second season than they did in their rookie season.

In fact, Evans has started to recover from his foot injury and is averaging 0.184 WP48 in the month of January (that statistic was Powered By NerdNumbers).

So, despite what the NBA coaches say, the adjustments they make to defend star rookies doesn't really stop them—unless they're injured.