A key part of the argument seems to be a comparison of REF ratings and citation metrics, which makes me a bit iffy about it. Still, well worth a look. Two bits that leapt out at me:
In general, if the actual REF grades are compared with those predicted based on citations, there is no apparent correlation. However, there is an evident trend that more theoretical/mathematical areas are favoured under REF compared with metric predictions, whilst more applied and human-centric areas are disfavoured.
In terms of the world rankings, an output in a more applied area, on average, needed to be in the top 0.5% (top 1 in 200) of its discipline to obtain a 4*, whereas in theoretical areas it was sufficient to be in the top 5% (1 in 20). That is, our panel scores did not at all reflect the assessment of global peers.
Finally, both the sub-areas of computing and the institutions disadvantaged by REF are those that tend to have a higher proportion of female academics. That is, the apparent disciplinary and institutional bias would be likely to create implicit gender bias. Indeed, amongst other things, HEFCE’s “The Metric Tide” revealed that the computing sub-panel awarded substantially more 4*s (top grade) to male authors than female ones, an effect that persists even once other explanatory factors considered.