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With free agency dominating Major League Baseball's offseason headlines, now is as good a time as ever to examine the most important free-agent signing in each franchise's history.

Players testing the open market began in the mid 1970s when rules allowing a team to control a player indefinitely were overturned.

Since then, players at the end of their contracts have been looking to cash in on their previous successes or renegotiate better terms. The era of free agency had a radical effect on the game, and its pull can still be seen today as the more wealthy teams throw their collective weight around in a bid to lure the best players to their clubs.

The average salary of players went from $45,000 in 1975 to $289,000 in 1983. Since then it has grown at an alarming rate.

As a side note, "most important" is not always synonymous with "best". Player A could have a statistically better season than Player B, but if the latter produced 80 percent of what Player A did but at 30 percent of the cost, there's an argument to be had.

I've tried to consider a range of factors. Performance is high on the list, but value-for-money is a close second. Also, I've tried to pick players who had a lasting impact with a franchise.

It's not always possible to find that perfect free agent who stuck around with a new club for a decade, and sometimes I've just gone with the guy who signed a one-year deal and put up MVP-like numbers. On other occasions, I've given my vote to a player picked of the scrapheap and transformed into an above-average ballplayer. It's not a science.

Not everyone will agree with this list and that's OK. It's subjective and open to debate and discussion. Feel free to let me know you you would picked.

If you don't like my opinions, don't worry. I have others.

Follow me on Twitter @AshMarshallMLB and @FantasyHardball