If you want to see the official PB of many champions, you cant understand their real strength. For example, Shaheen in 8 years (and 6 years undefeated in the World, with 27 following victories in 3000 steeple) ran 3000m flat once only, and not in shape (7'34" in Doha behind Kipchoge) cominh from typhous. His PB is 7'32" in 2009, when his shape was very far from what he was able to do during his best period (2003-2006). At his best, I suppose he could run under 7'25", may be 7'23", so the difference is between 28" and 30".
I can give you some evaluation about the best specialists I coached, during their best shape :
Christopher Koskei : 7'37" / 8'05" (28")
Richard Mateelong : 7'32" / 8'00" (28")
Julius Nyamu : 7'40" / 8'07" (27")
Wilson Boit Kipketer : 7'35" / 8' (with me, when he bettered the WR he was withou coach, after he was injured and came with me in 1999)
Elijah Chelimo : 7'43" / 8'10" (27")
David Chemweno : 7'40" / 8'09" (29")
Paul Kosgei : 7'35" / 8'07" (32") that's the reason because I moved him to longer distances, and he became World Champion in HM (2002) and bettered the WR of 25 km (2004), running HM in 59'07"
Ladies :
Dorcus Inzikuru : 8'46" official, but in 2005 I think 8'37" / 9'15" (but in that shape, with the situation of steeple of 2009, of sure she could run in 9'08") (41")
Ruth Bosibori : she ran her PB in the same period (August and September 2009) : 8'45" / 9'13" (28")
Durka Mana (Sudanese Record Holder) : 9'13" / 9'47" (34").
In my experience, the difference depends not so much on the technique, but on the ability in using for all the race a high percentage of the personal eccentric strength. Due to this fact, I used some specific training for increasing the eccentric strength, very important when the athletes lands after every barrier and especially in every water jump. I used few times technical exercises, for the simple reason that in Kenya (Iten) we don't have any barrier and any hurdle...
About 400m, I want to say an anedoct :
In the first edition of World Championships (Helsinki 1983) Alberto Cova won 10000m with the last lap in 53"2.
After one week, for fun but at his max speed, Alberto competed in a local race of 400m, as we were curious to see his real speed. He ran... 52"8!
So, we must understand that who is fast in his kick is not the fastest like speed, but who is able to use the highest percentage of his speed.
That's the reason because we speak about "sprint of the aerobic runners".
In other words, between people having the same level of specific endurance, of course the fastest goes to win. But this means that the first step is to reach the same level of endurance of the best athletes, and this is the right direction to work.
What are you doing with your speed, when you are not able to arrive together with the best runners at the end of the race ?