Yeah Jonathan wasnt as good on the SLJ as he was on the more rebound/reactive type more pure plyo work. As mentioned the eccentric/elastic strength elemtent. I trained with him the year he did his WR and can vouch for the information from pioneer.
There was a SLJ exhibition/competition around that time on the BBC sports personality programme where JE took on Martin Offiah (rugby league player) and someone else and Offiah won if I remember rightly.