It turns out that it's actually difficult to tell. The answer depends on how you define the word "strong". For example, does "strong" imply any of the following?
- strong because she plays quickly rather than taking days to consider her next move?
- strong because he has played lots of games against stronger players and has done well?
- strong because she doesn't rely on playing moves out on a board (or using analysis board feature under the Moves tab) to workout potential moves. Note: not that you could tell either way. But this does improve a players strength.
To get an indication of your opponent's strength consider a combination of the following:
- How many games have they played?
- What percentage of their games are wins?
- What was their highest rating?
- What was their best win and was that game a result of a blunder or timeout?
- What is the average rating of their opponents.
For example if your opponent has played 50+ games and is rated 1590 and the average rating of his opponents is one to two hundred points lower (1390) then I'd bet that your opponent is probably holding his own at 1590.
Take my current rating. At 1764, I've played 15 games. The average rating of my opponents is 1341. I'd say this is a strong indication that I'm probably not as strong as my rating would indicated. Don't get me wrong. I'm not saying the rating system is flawed. Anyone who has studied statistics can tell you that the sample population has to be meaningful. Meaning that it's harder to derive meaningful information from smaller data samples.
Why does any of this matter? Well, for one, if you're interested in improving your playing strength you should measure yourself against players who have solid ratings. Another benefit is that established players (those who have played many games) are less likely to be cheaters.
RD System (http://www.chess.com/forum/view/community/glicko-rd
) seems to be a good way to qualify the validity of a player's rating. Sadly I don't see the
RD on player profiles. Perhaps that information is only available to Premium members?