On a scale of playing gears from 0 to 10 where 10 is the absolute peak level we witnessed in last 20 years (Nadal's 2008 french open can be 10)
This is how the greats of the last 20 years operated ....
01. Federer IMO is the only Tennis player who regularly/or on most days operates on an avg at 8+ and above with least fluctuations, his highest gear can be 9.8-9.9 touched at Various years between 2004 and 2007.
02. Djokovic operates at 7.5 on an avg, in 1st week he is at 6.5 when he is a little vulnerable, by end of 2nd week he crosses 8.5 and reaches close to 8.8, his highest gear can be 9.8 reached during 2011 Aus Open.
03. Nadal outside clay operates on an avg of 7.0 and his highest gear was 9.0 at 2008 wimbledon & 2009 Aus open........ On clay his avg gear is 9.0, highest is 10.0 at the 2008 French Open and had he been pushed in that tournament then he had a 11th gear as well which we have never seen till date.
04. Safin operates at an avg of 4.5 and his highest gear can be 9.5+ which he attained at the 2000USO and 2005AO. Safin fluctuates a lot between these levels, you never know when he could beat you if in mood. At his best he could be a thorn for even GOATs who are operating at 9+.
05. Murray operates at an avg of 6.0 but his highest gear is only 7.5 (This explains why he reaches semis regularly but surrenders meekly, his ceiling is not high and thats why he is no ATG)
06. Hewitt operates at an avg of 5.5 but his highest gear is 7.5 which is same as Murray, hence they are similar players....
07. Roddick operates at avg of 5.0 but his highest gear is 8.8 which he reached at wimbledon 2009 final
08. Stanimal similar to Safin, has an avg of 5.0 but his highest gear is 8.8 which he reached at Aus open when he thrashed Novak and later took out Nadal in the final.
So kudos to Sir Andrew Barron Murray for having a very consistent level of play which does not dip below 6 but then his top gear is also under 8.
Hence his struggles would continue in 2000s as well since semi final opponents and finalist opponents would automatically be operating at a level of 8 or more. This is why Murray has been so impotent vs Fed since Fed's base level itself is higher than Murray's top gear
This pretty much sums up. Murray had solid average level which made him very consistent player for years. But he lacked upper gears - so he could convert very few out many opportunities (20+ semis).