......resulting in an average of 37.69 from 110 tests with 29 against the windies, 31 against the aussies, 41 and 43 against pakistan and south africa respectively(the best attacks of that time)...he certainly had a good technique and good temperament, but just didn't have the consistency to deserve your "sustained excellence" remark....
The number 37.69 is a pretty meaningless one. What's far more important is this:
season 1990 6 11 0 735 66.81
season 1990/91 5 10 1 279 31.00
season 1991 5 9 0 79 8.77
season 1992 3 5 0 145 29.00
season 1992/93 2 4 0 63 15.75
season 1993 6 12 0 553 46.08
season 1993/94 5 9 0 510 56.66
season 1994 6 10 0 480 48.00
season 1994/95 5 10 0 407 40.70
season 1995 6 12 0 488 40.66
season 1995/96 5 8 1 390 55.71
season 1996 6 10 1 425 47.22
season 1996/97 3 4 1 325 108.33
season 1997 6 12 1 257 23.36
season 1997/98 6 11 0 199 18.09
season 1998 5 10 1 493 54.77
season 1999 2 4 0 133 33.25
season 1999/00 5 8 0 225 28.12
season 2000 7 12 0 536 44.66
season 2000/01 3 6 1 341 68.20
Overall 97 177 7 7063 41.55
TBH, I couldn't care two hoots about the series I've knocked-out - he played in 1989 when there's no way on Earth he should have because he was just out of University and the side was in total chaos, and he had a downward spiral towards the end of his career, which really doesn't matter for someone who's been excellent for 97 Tests. Nor do the series in Zimbabwe in 1996 and Australia in 1998\99 have the slightest relevance, because he was barely half-fit for either.
That, therefore, is just 2 periods of any length where he had a genuinely bad time - 1991 against West Indies, where it should be noted his back was far from in tip-top condition, and the 1997-1998 time, which, unfortunately, happened to coincide with playing 2 excellent attacks in Australia and West Indies.
Other than those, however, you might just see what I mean about sustained excellence, given that he rarely failed for any extended time.