Le breton said:I thought he admitted to taking amphetamines and cortisone
That's also my understanding. However, would that + his injuries be enough to explain his highs and lows? I tend to think he left out big chunks of his doping history.
Before 1991 and big scale EPO usage it's hard to find among really big cycling stars somebody with so huge fluctuations in form.
In a good day he could beat Herrera on an uphill TT, yet on the Ventoux TT (TdF) on July 19, 1987, he finished 9:09 behind Jeff Bernard (7:30 behind Herrera) in 64th position out of 164 racers. One could find many examples of his staggering highs and lows.
Meh:
Even those following a full regimen can have a bad day. Now in Laurent's posituin there are a view decent explanations possible:
1.he just came back after a disastrous injury
2. he wasn't competing, so he let go
3. he was competing, heart the first few times and let go
4. Laurent was a contender in the ardennes classics, so he peaked horribly wrong
Keep in mind he needed 86, 87 and 88 before he truly returned, even though he did show glimmers of his class (winning the Fleche Wallonie). In 89 he had a superbe year, with a giro win and a 2nd place in the TdF. After that he faded towards a classic specialist.
And there are several very known riders who had extremely fluctuating years, especially in GT's. Without even looking into it, those three come up:
Kelly, Fignon, Roche all managed to win one or more GT's and swap that with years where they were shadows of themselves (GT wise).