The Giants' acquisition of third baseman Evan Longoria ranks among the biggest trades in baseball this offseason.

And Longoria probably won't be the club's last major addition before Spring Training.

The Giants and Reds remained in active communication on Tuesday about a trade that would send center fielder Billy Hamilton to San Francisco, sources told MLB.com.

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In trade conversations, the Reds have shown interest in outfielder Heliot Ramos, ranked as the Giants' No. 3 prospect by MLBPipeline.com, as first reported by The Athletic and subsequently confirmed by one source to MLB.com.

Although the Giants already have one of the Majors' largest payrolls for 2018, general manager Bobby Evans still has substantial work to do with the club's outfield. After the trade of Denard Span to the Rays, the Giants do not have an outfielder on their 40-man roster who was a league-average (or better) offensive player in 2017, as determined by adjusted OPS.

For the record, Hamilton wasn't, either. His .634 OPS in 2017 was the second lowest of the four Major League seasons in which he has played at least 100 games. But Evans has spoken of prioritizing elite defense in center field, given AT&T Park's unique dimensions, and Hamilton would provide that. Hamilton has been the most valuable defensive center fielder in baseball over the last four seasons, according to FanGraphs.com.

Hamilton, 27, also would bring speed and excitement to what was the National League's oldest group of position players in '17. He's set to be arbitration-eligible in '18 and '19 before becoming a free agent for the first time, which would give the Giants a measure of cost certainty over the next two seasons. That's significant, because San Francisco also would like to add a corner outfielder to a lineup that ranked at the bottom of the Majors in home runs this past season.

A reasonably priced center fielder, such as Hamilton, should enable Evans to pursue more expensive corner outfielders, such as Andrew McCutchen (via trade) or Lorenzo Cain (as a free agent).

The Giants likely would have very different priorities at this stage of the offseason if they had acquired Giancarlo Stanton from the Marlins. The teams had a trade agreement in place before Stanton, now with the Yankees, used his no-trade clause to block a deal to San Francisco.

Jon Paul Morosi is a columnist for MLB.com.