Explanation:
there are no repetitions (there are not multiple copies of the same player).
and the sequence (or order) of the selected players does not matter (p1, p2, p3, p4, p5 is the same as e.g. p3, p5, p1, p2, p4).
so, we have the combinations of 5 out of 16 items :
C(16, 5) = 16!/(5! × (16-5)!) = 16!/(5! × 11!) =
= 16×15×14×13×12/(5×4×3×2) =
= 4×3×14×13×2 = 4,368
there can be 4,368 different groups.