The Spitfires were not massacred, what gives you that idea?
If we factor in all air combats over North West Australia, not just the attacks on escorted bomber formations, then 1 Fighter Wing wrote off 28 Japanese aircraft (15 bombers, 7 reconnaissance aircraft and 6 fighters) losing 28 Spitfires in the process. This 1:1 exchange ratio is typical of average squadrons during the first half of the war, similar to many fighter squadrons in the BoB, and much better than the Spitfire V squadrons based in England in 1941-42.
The Wing's loss rate of 11%-12% is almost identical to comparable USAAF units, the 49th FG suffered a loss rate of 11%. It was worse than the best USAAF units in theatre.
The reasons for the Wing's problems are many. Primarily a lack of training. In seven operations the Spitfire pilots made 126 gunnery passes but shot down just 14 bombers. Their gunnery was terrible, compounded by problems with the cannon jamming. The cannons typically jammed in the first two to three seconds of firing, leaving the Spitfires with just .303 machine guns when they finally closed the range. One of the few things Caldwell got right was a request for the Spitfires to be armed with .50 calibre Brownings, but this was quite impossible at the time.
There were also tactical deficiencies. Going after the bombers left the Spitfires vulnerable to a bounce, they did not have the luxury of other units as high cover as they might have had in Europe. This was compounded by poor training and the inability of the pilots to operate in pairs. The deficient 'look out' that resulted from this left them even more vulnerable than they needed to be.
As Anthony Cooper explains
"...the credit side of 1 Fighter Wing's tally sheet was thinned out by systematic gunnery problems, while the debit side was swollen by endemic procedural deficiencies."
1 Fighter Wing's performance was not brilliant, but it was no worse than that of most contemporaries in other theatres. It could have been better were it not for the issues sumarised above.
Cheers
Steve