The problem with the one and dones... is the trickle-down effect. If five kids didn't leave UK early every year, that means five incoming kids would have to have gone elsewhere. Over the course of 4 years.. that is 20 kids. Similarly, if Flynn, Dion, MCW, Ennis, Grant, etc., hadn't left early, some kids who came here would have to have gone elsewhere.
The trickle down effect from the one and dones (and the other early departures) are a major reason for the decline in quality of play in CBB. It is not just the one and dones themslves
This factor however cannot really explain the decline in basketball from about 2005 to now. Early entries are not some new phenomenon. They exploded around 2000, and have not dramatically increased since the 2001 draft.
http://www.nba.com/news/lottery02_earlyentry_history.html
2001 NBA DRAFT EARLY ENTRY CANDIDATES
Player School/Country Year/DOB Drafted By (Round/#)
Gilbert Arenas Arizona Sophomore Golden State (2nd/31)
Brandon Armstrong Pepperdine Junior Houston (1st/23)
Malcolm Battles New Mexico Junior Not drafted
Tavorris Bell Rhode Island Junior Not drafted
Preston Bennett Grayson C.C. (Texas) Freshman Not drafted
Keith Bogans Kentucky Sophomore WITHDREW
Michael Bradley Villanova Junior Toronto (1st/17)
Jamison Brewer Auburn Sophomore Indiana (2nd/41)
Kedrick Brown Okaloosa-Walton C.C. (Florida) Sophomore Boston (1st/11)
Kwame Brown Glynn Academy H.S. (Ga.) H.S. senior Washington (1st/1)
SirValiant Brown George Washington Sophomore Not drafted
Nick Burwell Orange Coast College (Calif.) Sophomore Not drafted
Goran Cakic Radnicki (Yugoslavia) 1980 WITHDREW
Tyson Chandler Dominguez H.S. (Calif.) H.S. senior LA Clippers (1st/2)
Ousmane Cisse St. Jude Catholic H.S. (Ala.) H.S. senior Denver (2nd/47)
Sam Clancy Southern California Junior WITHDREW
Jason Collins Stanford R.S. Sophomore Houston (1st/18)
Omar Cook St. John's Freshman Orlando (2nd/32)
Eddy Curry Thornwood H.S. (Ill.) H.S. Senior Chicago (1st/4)
Samuel Dalembert Seton Hall Sophomore Philadelphia (1st/26)
Edwin "Greedy" Daniels Texas Christian Junior Not drafted
Carlos Delfino Reggio Calabria (Italy) 1982 WITHDREW
Jefferson de Souza Sobral Vasco da Gama (Brazil) 1980 WITHDREW
Boris Diaw Pau Orthez (France) 1982 WITHDREW
DeSagana Diop Oak Hill Academy (H.S.) (Va.) H.S. Senior Cleveland (1st/8)
Patrick Doctor American Junior WITHDREW
Corsley Edwards Central Connecticut Junior WITHDREW
Denis Ershov Spartak (Russia) 1981 Not drafted
Maurice Evans Texas Junior Not drafted
Benjamin Eze Southern Idaho Freshman Not drafted
Alton Ford Houston Freshman Phoenix (2nd/51)
Antonis Fotsis Panathinaikos (Greece) 1981 Memphis (2nd/48)
Joseph Forte North Carolina Sophomore Boston (1st/21)
Jason Gardner Arizona Sophomore WITHDREW
Pau Gasol .C. Barcelona (Spain) 1980 Atlanta (1st/3)
Jerry Green Cal-Irvine Junior Not drafted
Eddie Griffin Seton Hall Freshman New Jersey (1st/7)
Rob Griffin Iowa Junior Not drafted
Rashid Hardwick Eastern Oklahoma State Freshman Not drafted
Trenton Hassell Austin Peay Junior Chicago (2nd/30)
Kirk Haston Indiana Junior Charlotte (1st/16)
Draper Housley Lee College (Texas) Sophomore Not drafted
Steven Hunter DePaul Sophomore Orlando (1st/15)
Vlado Ilievski Antalya (Turkey) 1980 WITHDREW
Robertas Javtokas Lietuvos Rytas (Lithuania) 1980 San Antonio (2nd/56)
Richard Jefferson Arizona Junior Houston (1st/13)
Joe Johnson Arkansas Sophomore Boston (1st/10)
Tony Key Centennial H.S. (Calif.) H.S. Senior Not drafted
D.A. Layne Georgia Junior Not drafted
Reo Logan Miami (Fla.) Freshman WITHDREW
Raul Lopez Real Madrid (Spain) 1980 Utah (1st/24)
Arvydas Macijauskas Lietuvos Rytas (Lithuania) 1980 WITHDREW
Tito Maddox Fresno State Freshman WITHDREW
Zach Marbury Rhode Island Junior Not drafted
Jamario Moon Meridian C.C. (Miss.) Sophomore Not drafted
Troy Murphy Notre Dame Junior Golden State (1st/14)
Bostjan Nachbar Pivovarna Lasko (Slovenia) 1980 WITHDREW
Lazaros Papadopoulos Iraklis (Greece) 1980 WITHDREW
Tony Parker Paris Basket Racing (France) 1982 San Antonio (1st/28)
Tayshaun Prince Kentucky Junior WITHDREW
Vladimir Radmanovic FMP Zeleznik (Yugoslavia) 1980 Seattle (1st/12)
Zach Randolph Michigan State Freshman Portland (1st/19th)
Jason Richardson Michigan State Sophomore Golden State (1st/5)
Kenny Satterfield Cincinnati Sophomore Dallas (2nd/54)
Luis Scola Tau Ceramica (Spain) 1980 WITHDREW
Mladen Sekularac FMP Zeleznik (Yugoslavia) 1981 WITHDREW
Bobby Simmons DePaul Junior Seattle (2nd/42)
Jawan Simpson Puget Sound Christian College Freshman WITHDREW
Derick Singleton St. Paul's College (Va.) Junior WITHDREW
Will Solomon Clemson Junior Memphis (2nd/33)
Clifton Terry Kennedy-King College (Ill.) Sophomore Not drafted
Gerald Wallace Alabama Freshman Sacramento (1st/25)
Rodney White Charlotte Freshman Detroit (1st/9)
Damien Wilkins North Carolina State Sophomore Not drafted
Michael Wright Arizona Junior New York (2nd/39)
So if one were to argue that college basketball has become markedly worse the last 10 years one would have to find another factor. That was my point -- people are putting the one and done as way too big a factor for the recent decline.
There have to be other larger factors for the recent decline since 2005.