just been checking some eaves stats and my suspicion proved accurate.
just looking at league games, he's made 28 starts and 42 appearances from the bench. in 28 starts, he's scored 3 times, giving a strike rate of 10.7%. in 42 sub appearances, he's scored 7 times, giving a strike rate of 16.7%.
i haven't done any calculations about on-field time, but if i assume he played the full 90 minutes when he started, that's a goal every 840 minutes (3 in 2520 mins). if i assume his sub appearances typically happened halfway through the second half (most were quite a bit later - maybe 15 minutes on the pitch is more typical, but i'll stick with 22.5 minutes), that's seven goals in 945 minutes, or a goal every 135 minutes. so when he comes on as sub, his scoring rate is 6.22 times better than when he starts matches. if his rate for full appearances matches his rate off the bench, he'd have scored 18 or 19 goals in his 28 starts instead of the 3 he has managed.
if i assume his average pitch time off the bench is 15 minutes rather than 22.5 minutes, and if he had scored at that rate in games he starts, that would make his strike rate a goal every 90 minutes and his 28 starts would have produced 28 goals.
so why isn't it?