Let's remember that characters such as Worf have successfully wrestled with individual Borg Drones (and Data shrugs them off with ease, except perhaps in "Descent" where the seeming unease might be more psychological than physical) - yet a group of Drones was able to wrestle Data out of balance and drag him away in ST:FC.
While Data clearly has more strength than any other humanoid-shaped character we have witnessed, five more or less "normal-strength" opponents might plausibly defeat him by the above method. Even if Data managed to incapacitate two of them, the remaining three might lift him off the ground and deny him leverage, then proceed to bash him to bits with blunt objects.
That's another interesting question right there, though: how vulnerable is Data, really? We have seen that the skin around his skull can be peeled off with a hard blow (say, in "Thine Own Self"), but the structures beneath seem none the worse for the wear. We have seen a light machine gun pepper his midbody for several seconds, with no ill effects, so presumably the bullets didn't penetrate. Various explosions have separated his body parts, though, and the simple mechanical force of falling from a height of perhaps ten meters was enough to rip off the arm of another Soong android, Juliana Tainer, in "Inheritance". Quite possibly, the five Jem'Hadar could turn Data into a collection of four spasming limbs, one helpless torso, and one head that shouts insults at them like the Black Knight from the Monty Python sketch.