Adding this to put a bit more weight on the very real dangers of lightning strike.
Is it possible that a lightning strike could have affected so many players in a single strike?
Yes, definitely plausible.
Lightning does not need to hit someone directly to have severe consequences. A "near miss" is all it takes.
The concussive force of a lightning's shockwave alone is significant. Depending on lightning strength, the shockwave can reach the equivalent of 30kg TNT.
(Iris Hammelmann: "Alltagsphänomene: unglaublich aber wahr" (engl. "Everyday phenomenons: Unbelievable but true"). Compact-Verlag, 2008, ISBN 978-3-8174-6411-1 -- Link lifted from the German Wikipedia article on Lightning)
(Don't picture a box on the ground, picture a length of detcord strung between the ground and the clouds. Still a pretty significant blast if you're up close. I found several sites warning of the shockwave while mountaineering.)
A second effect is the electric current generated inside your body if touching the ground in two separate locations -- this is called "step voltage", and can amount to 1000 V and more.
And third, shock also plays into it.
So much for the physics. As for life footage evidence:
Would it require hospitalization, and if so, could they be expected to return to play?
Depending on circumstances, such an event can range in effect from shock and some discomfort to fatalities.
Is this a plausible excuse?
I don't know if the result was so surprising it required an "excuse", but yes, it is plausible. One could check the weather databases and hospital records if really interested, but I don't know if the event would be worth the effort.