Most of us who fly it, know the 737 can stop on occasion in under 1000 metres if you try hard, so I agree with andrasz about the most probable areas to be looking. As safety pilot I would be asking:
. did they use flaps 40
. was autobrake 3 or max selected
. was speed within limits, with appropriate vref
. was the approach fully stable
. did they touch down firmly in the touchdown zone
. did they immediately select full reverse
. was there any premature use of the steering tiller
Going around when it is still possible is with hindsight normally the best option and strongly recommended everywhere, but still pretty rare. Fortunately nobody got hurt on this occasion. But there have been quite a few 737 overruns with perfectly serviceable aircraft recently and the Air India Express accident demonstrates what can happen in the worst case. If we all decided we could not land on wet 2000 metre runways we would be out of a job pretty quick!