“You are what your record says you are” means that the record speaks for itself. A team with a good record is not overrated and a team with a bad record is not underrated. All teams have injuries and that doesn’t excuse a poor record.
 
The saying is attributed to NFL football coach Bill Parcells (who coached both the New York Giants and the New York Jets), but “you are what your record says you are” was cited in 1994, when Parcells was head coach of the New England Patriots. “You are what your record says you are, and never mind how you got that way” was cited in a professional football story in the San Diego (CA) Union in 1978, so Parcells might have heard the saying from someone else.
 
   
Wikipedia: Bill Parcells
Duane Charles “Bill” Parcells (born August 22, 1941) is a former American football head coach, both in college with the Air Force Falcons, and the National Football League with the New York Giants, New England Patriots, New York Jets, and Dallas Cowboys and is currently a “Courtesy Consultant” for the Cleveland Browns. He is known as “The Big Tuna”, a nickname about the shape of his physique derived from a team joke during his tenure as linebackers coach of the New England Patriots.
 
16 October 1978, San Diego (CA) Union, “Chargers Get Foes’ Praise, Not Victories” by Wayne Lockwood, pg.C-1, col. 6:
There are no asterisks awarded in the standings for “good effort.” You are what your record says you are, and never mind how you got that way.
 
3 January 1994, The Intelligencer (Doylestown, PA), “Blaming it on injuries doesn’t wash anymore” by Reuben Frank, pg. B-8, col. 4:
A wise man with a bad football team and a Super Bowl ring once said, “You are what your record says you are.”
 
That man was Bill Parcells, longtime head coach of the New York Giants, first-year coach of the New England Patriots.
 
Parcells’ point? That nobody wants to hear about injuries or bad breaks or crazy bounces or poor officiating or tough schedules. Your record is your record. You are what you are.
 
6 October 1994, The Advocate (Stamford, CT), “Boomer must deliver more for the Jets” by Mike Lupica, pg. B8, col. 1:
Bill Parcells has always said, “You are what your record says you are.” He never wanted to hear about excuses or bad breaks or bad bounces. You are what your record says you are.
 
Google News Archive
16 October 1994, The Spokesman-Review (Spokane, WA), “Thrown for a loss” by Gerald Eskenazi (New York Times), pg. C5, col. 3:
That brings home one of Parcells’ sayings: “You are what your record says you are.”
 
Google News Archive
2 December 1997, Sun Journal (Lewiston, ME),  “Patriots have been big tease” by Bill Reynolds (Providence Journal-Bulletin), pg. C1, col. 1:
Parcells liked to say “You are what your record says you are,” when asked about his team.
 
Google News Archive
26 December 2000, Lodi (CA) News-Sentinel, “Giants can rest after securing top seed” (AP), pg. 18, col. 1:
“You have to look at the record, 12-4 got the No. 1 seed in the NFC,” Fassel said. “I don’t see how anyone can say “Well, they’re not one (of the elite).’ I have always believed you are what your record is.”
(New York Giants head football coach Jim Fassel.—ed.)
   
Google News Archive
14 December 2004, Victoria (TX) Advocate, “Cowboys,” pg. 2B, col. 4:
But as Parcells says, you are what your record says you are.
 
Google Books
Parcells:
A Football Life
By Bill Parcells and Nunyo Demasio
New York, NY: Crown Publishing Group
2014
Pg. ?:
Still, even with their poor record, the Jets were among the NFL leaders in turnover differential, generally the indicator of a good team. Of course, you are what your record says you are.
 
Google Books
Parcells:
The Unauthorized Biography
By Carlo DeVito
Chicago, IL: Triumph Books LLC
2014
Pg. 108:
One of the things Parcells liked to say was, “You are what your record says you are.”
     
Daily News (New York, NY)
Woody Johnson says it was ‘obvious’ Jets had to make change
BY SETH WALDER   Monday, December 29, 2014, 3:04 PM
On the day that Woody Johnson fired both Rex Ryan and John Idzik, the Jets’ owner was candid about the team’s recent shortcomings.
(...)
“It became pretty apparent during the season, as we progressed, the team was not getting better,” Johnson said. “As (Bill) Parcells said, you are what your record says you are. It was kind of obvious that we had to make a change. It was obvious to me anyway.”