Pride was the same way. They never brought in new fighters. The guys they had who were at the top in 2001 were the same guys at the top in 2007.
Complete and utter bullshit, Pride brought in tons of guys in after 2001 who got to fight the top guys in the division -- I'd argue they signed better fighters between 2002-2006 than the UFC did.. some examples
HW: Werdum (2005), Kharitonov (2003), Hunt (2004), Barnett (2004), Fedor (2002), Aleks (2003)
LHW: Shogun (2003), Nakamura (2003), Diet Nog (2002), Sokoudjou (2007), Overeem (2002), Yoshida (2003)
I'll ignore the fact they built 2 more divisions (LW and MW) after 2001, not to mention the countless guys who came in and didn't make it to the top.
Semmy Schilt is a classic example of how far K-1 has declined. Went went into kickboxing and left because he wasnt that good. Then went back after he couldnt make it past gate keeper in MMA. How can you be so sure he is good? He fights the same guys over and over which is a common theme in K-1. He has fought JLB 4 times, Aerts 4, Remmy 3, Hoost 3. He has over 20 fights with only 7 different guys. He also got smashed on the feet by Gilbert Yvel back in the day.
Schilt improved drastically between 1996 and 2004 (and he still lost to Ignashov in 2004). Schilt was always a ridiculously difficult opponent under 3 knockdown rules, simply because he doesn't even need to connect cleanly. Also Yvel was a pretty decent striker in his own right; just really unreliable and prone to acts of extreme stupditiy.