Let's say there are two players A and B, both of them used to be team-mates and are retired now.
In the given context, is the use of "since" correct here?
Both A and B played against each other 6 times since they got separated in the year 2006, and player B dominated those games winning 75% of those.
I want to know whether "since" is correct here. I have seen "since" being used in present perfect tense, as in They have met each other 6 times since player B signed for team C.
Since in this context means after (i.e. - after some time explicitly or implicitly identified in supporting text). It might help OP to imagine replacing since with after the time at which in both his examples.
In other contexts, since can mean because, but that's really just a metaphoric extension of the above.
I think what's bothering OP is that since has many subtly different usages. Here are just a few from OED:
1: During the period between (a specified time) and now; at some time subsequent to or after.
2: Ever or continuously from (a specified time, etc.) till now.
3: Denoting a point of time to which the action or event mentioned is subsequent.
4: In sentences implying continuity of action or fact during the period indicated. Also with ever, and (rarely) with that.
Most (but not all) senses imply continuity from whatever time in the past is indicated by since, up to now. For example, "I have known John since we were children" is a very common context, and we normally use past perfect there because we still know him now.
But suppose you were at John's funeral? It would be perfectly grammatical to say "I knew John since we were children" (you don't really know him any more, since he's dead). I suspect many native speakers might have the same misgivings as OP, but I think it's just because we're more used to contexts where there is continuity into the present. FWIW, I think I might be tempted to say I knew him since when, or even since way back when, to distance myself from the standard up till now/ever since then implication.
It depends on how the writer views the events described. As drafted, the sentence uses the past tense in both the main clause and the since clause to locate both the six matches and the separation firmly in the past. The writer is taking an historical perspective.
If, however, the six matches were relevant to something the writer was saying was happening now, or was going to happen in the future, then a perfect construction would be required. An example might be ‘Both A and B have played against each other 6 times since they got separated in the year 2006, so there’s every chance that they will do so again.’
