It's pretty hard to know what exactly Ferrari was up to during FP1 and FP2, they never did true race sims, no true quali sims, mostly ran around doing a push lap then a charge lap. Leclercs lap in FP1 came after doing the push/charge about 5 times, so his tyres were certainly not in any sort of sweet spot.
Comparing Russell's performance in his mini race sim and Hamilton's 5 lap stint at the end of FP2, the major difference is deployment IMO, especially out of turn 2 and turn 10.
