You hear a lot about the idea of a sophomore slump -- productive rookies falling off a year later. But how common is it? I took a look at how running backs have fared this century. Later in the week I'll do the same with wide receivers.

There's no definitive threshold for what constitutes rookie year success, but I went with running backs who rushed for over 800 yards in their first seasons. Since 2000, there have been 56 first-year backs to have done so, including four in 2022: Dameon Pierce (pictured), Isiah Pacheco, Kenneth Waker and Tyler Allgeier.

Table shows each of those players' rookie year stats, including their fantasy rank in PPR leagues, and how they fared the next season -- run, rec, TD and fantasy ranking in Year 2. Two of those players (Jamal Lewis and J.K. Dobbins) missed their entire second seasons due to injury.

Of the other 50 players, just over half (27) came back and rushed for at least 800 yards again. That's respectable. But nearly as many (24, including the two who missed the entire season, and a whole bunch of other injured guys) declined by at least 300 rushing yards in their next seasons. Not all of those players were disappointments (6 were top-20 fantasy backs), but enough of them were to explain why the notion of a sophomore slump is so popular.

In the table, sorted by Year 2 rushing yards, running backs who declined by at least 300 rushing yards in their second seasons are tagged with black dots.

800-YARD ROOKIE RUNNING BACKS, ONE YEAR LATER (2000-)
YearPlayerRunRecTDRkNxt(Ru-Re-TD)Rk
2008Chris Johnson, Ten.122826010112006-503-161
2020Jonathan Taylor, Ind.11692991261811-360-201
2007Adrian Peterson, Min.13412681351760-125-109
2001LaDainian Tomlinson, S.D.12363671061683-489-152
2002Clinton Portis, Den.15083641771591-314-146
2018Nick Chubb, Cle.99614910171494-278-88
2013LeVeon Bell, Pitt.8603998151361-854-111
2012• Alfred Morris, Was.1613771371275-78-720
2003Domanick Williams, Hou.10313518141188-588-143
2013Eddie Lacy, G.B.11782571181139-427-136
2008Jonathan Stewart, Car.8364710331133-139-1115
2016Jordan Howard, Chi.13132987101122-125-915
2006Joseph Addai, Ind.10813258131072-364-154
2019David Montgomery, Chi.8891857241070-438-104
2019Josh Jacobs, Oak.11501667211065-238-128
2007Marshawn Lynch, Buff.11151847161036-300-913
2021Najee Harris, Pitt.12004671031034-229-1014
2018Phillip Lindsay, Den.103724110131011-196-720
2005Ronnie Brown, Mia.9072325231008-276-522
2018• Saquon Barkley, NYG13077211521003-438-811
2004Julius Jones, Dall.819109731993-218-519
2016• Ezekiel Elliott, Dall.1631363162983-269-912
2008• Matt Forte, Chi.1238477122929-471-412
2018Sony Michel, N.E.93150634912-94-731
2015Todd Gurley, St.L.1106188109885-327-615
2019Miles Sanders, Phil.818509615867-197-623
2017• Kareem Hunt, K.C.1327455114824-378-1412
2005• Cadillac Williams, T.B.117881621798-196-136
2014• Jeremy Hill, Cin.1124215910794-79-1220
2010LeGarrette Blount, T.B.100714634781-148-533
2009Knowshon Moreno, Den.947213918779-372-818
2006Maurice Jones-Drew, Jac.941436168768-407-1011
2020• James Robinson, Jac.1070344107767-222-824
2008Kevin Smith, Det.976286817747-415-521
2001• Anthony Thomas, Chi.1183178717721-163-634
2004• Kevin Jones, Det.1133180621664-109-532
2011DeMarco Murray, Dall.897183230663-251-426
2012• Trent Richardson, Cle.950367128563-316-432
2002• William Green, Cle.887113633559-50-149
2020• Clyde Edwards-Helaire, K.C.803297522517-129-643
2012• Doug Martin, T.B.1454472122456-66-157
2017• Leonard Fournette, Jac.10403021010439-185-641
2008• Steve Slaton, Hou.1282377107437-417-727
2015• Thomas Rawls, Sea.83076537349-96-361
2013• Zac Stacy, St.L.973141821293-152-168
2021• Elijah Mitchell, S.F.963137626279-7-282
2021• Javonte Williams, Den.903316717204-76-081
2001• Dominic Rhodes, Ind.11042241012157-62-191
2012• Vick Ballard, Ind.81415233363-(-5)-0132
2000• Mike Anderson, Den.14871691511386-167-444
2020• J.K. Dobbins, Balt.805120924Injured--
2000• Jamal Lewis, Balt.1364296618Injured--
2022Dameon Pierce, Hou.939165525??????
2022Isiah Pacheco, K.C.830130537??????
2022Kenneth Walker, Sea.1050165918??????
2022Tyler Allgeier, Atl.1035139430??????

If we want to go strictly by fantasy ranking, slightly over half (27) of those 52 came back and put up top-20 numbers in their second seasons, and six more at least finished in the top 30. That's about 63 percent who were quality starters in Year 2. I think we can say that sophomore slumps are real, but not daunting enough that anyone should be afraid to draft Pierce, Pacheco, Walker and Allgeier on that basis. Statistically speaking, 2-3 of them should be pretty good again in 2023.

--Andy Richardson