I loved how this play allows for Entaro to put it into perspective that he truly loved baseball. Not everyone will become a pro in a certain field, and he reached his limit. But he had a blast, but of course having a limit and understanding it can be difficult to cope with.
The light showing on stage is regarding a new opportunity, and for him it is acting. As the play talks about a dream, acting can be seen as an escape for Entaro. For him, it always helps him to express himself from everything he may be suffering.
No surprise he wants to know if Ryuji was watching.