second baseman vs second sacker

second baseman and second sacker both are nouns.

Word	Noun	Adjective	Verb	Adverb
second baseman	Yes	No	No	No
second sacker	Yes	No	No	No

As nouns, second baseman and second sacker are synonyms defined as:

second baseman and second sacker: (baseball) the person who plays second base

second baseman (noun)	second sacker (noun)
(baseball) the person who plays second base	(baseball) the person who plays second base