“Don’t believe what you see in September” (baseball adage)

“Don’t believe what you see in March/April/September” is a baseball adage. March is spring training, April is the first month of the baseball season, and September is the last month of the baseball season. The results during these months might be abnormal.
 
“But haven’t we always been told by the baseball experts that you can’t believe what you see in September?” was cited in 1991. The “never-believe-what-you-see-in-March rule” was cited in 1992. It’s not known if any particular person coined the saying, although baseball manager Billy Martin (1928-1989) was credited in 2009.
 
 
25 August 1991, Courier-Post (Camden, NJ), “Front office isn’t fooled by Phils’ success” by Bob Brookover, pg. 3F, col. 2:
But haven’t we always been told by the baseball experts that you can’t believe what you see in September?
         
3 May 1992, The Times (Trenton, NJ), “Reds’ Charlton is really nastier than he should be” by Dan Castellano, pg. C9, col. 5:
Violating the never-believe-what-you-see-in-March rule, the Cubs let him start the season as their third baseman.
 
4 September 1999, Florida Today (Cocoa, FL), “Bullpen botches Burnett’s outing” by John Bells, pg. 6C, col. 4:
“You can’t always believe what you see in September, but you get a better idea about pitchers than you do about hitters.”
(Spoken by Marlins manager John Boles.—ed.)
 
Sun-Sentinel
30 April 2001 South Florida Sun-Sentinel (Fort Lauderdale, FL), “Tme for Marlins to show us their stuff” by Dave Hyde, pg. 1C:
And this platform coincides with the first season this team is developed again. Or will develop. Or is supposed to develop. Maybe. What is the old baseball saying, don’t believe what you see in April and September?
 
Yankee Tradition
April 6, 2009
It’s 1923 All Over Again; Yanks To Christen New Stadium With Championship
(...)
Billy Martin always said don’t believe what you see in September and March, but I honestly feel the Yankees have a very good pitcher in Coke.
     
Twitter
Anish Shroff
‏@AnishESPN
@Alexi_G Old adage in baseball - don’t believe what you see in April… and don’t believe what you see in September… patience
10:23 PM - 25 Apr 2010
 
Twitter
(((Jesse Spector)))
‏@jessespector
Old baseball adage: “Never believe what you see in April or September.” So, congratulations to the 2011 world champion Red Sox!
11:11 PM - 28 Sep 2011
 
Daily News (New York, NY)
Girardi says Montero must earn his stripes
BY MARK FEINSAND   BLOGGING THE BOMBERS Thursday, December 8, 2011, 12:26 PM
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The old baseball adage is to not believe what you see in September, but Girardi puts stock into Montero’s performance given that the Yankees were in the middle of a pennant race during his debut.
     
Twitter
James Piccoli
‏@JamesPiccoli
Saying In Baseball Don’t Believe What You See In March and September; Is It The Same During Non Consequential Games Late In Football #ODB
3:05 PM - 14 Dec 2014
 
Bronx Baseball Daily
Blue Jays intensify AL East race with J.A. Happ signing 16
28 Nov, 2015 in MLB News and Notes / Yankees News by Delia Enriquez
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COMMENTS
YankeezFan
Im glad the Jays brought back JA Happ, he has been a bad pitcher for 4 years, was a terrible pitcher last year in a pitcher friendly ball park, until he went to the Pirates, and played teams that were already eliminated from contention, and pitched well for 4 weeks. The old adage in baseball is that don’t trust what you see in September and April.
   
Mark Bradley blog
Remember how bad the Braves were? They’re not so bad now
By Mark Bradley
September 20, 2016
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COMMENTS
DawgDadII
Yes, there are some encouraging signs in the starting lineup, but there IS the old adage “never trust what you see in September”. Winning games now is better than losing, but this season is still a blight in the record books.