A professional athlete / cricketer should always, and I mean always, be judged on the metrics that he churns out in any and all professionally conducted games or events. If these games are weighted by the ICC as matches that will be recognized in their professional essence then clearly any amount of runs / wickets, scored or taken respectively will have the same weightage as that against any other ICC full member.
The other part of your OP which states the impact of performance et al. Well, I can't speak for others as I do not want to parade in on another man's opinion however IT IS A FACT that Inzaman DOES NOT average 50 in test cricket ~ there are no two ways about it. Similarly if someone fails to perform here then, as a matter of my own opinion, I firmly believe it should be treated as a dip in form and the correct necessary measures taken subsequent to these 'hypothetical' failures.
I am not too sure about the role of statisticians here and how they might view it however, as a Data Analyst and someone who does number crunching for living I can assure you that conclusions on a progression will forever be inaccurate if the sampling process has selection bias. In determining a number series to successfully identify trends an Analyst cannot:
1) Assume factors that might or might not have taken place
2) Have a preconceived notion or a target line before running a progression
These are the two main pitfalls when someone decides to take in, 'statistics' as per say into considering for showing valid criticism or showing some sort of athletic peak. It's actually extremely simple, for accurate and unbiased results one must always sample across the board without any prejudice.
