There is little that I can write with respect to the legacy of Gil McDougald that was not beautifully enumerated in his obituaries in The New York Times and The Daily News, respectively. In a narrative sense, at the very least, the memory of McDougald has been preserved quite well - particularly considering his rather brief, unheralded career. Many Yankees fans are well aware of McDougald, be it for his positional flexibility or his five World Series rings, and he is usually brought up whenever an 'All-Time Yankees' team is constructed. And yet, I cannot help but feel like his greatness - and, yes, greatness is the correct term - has been forgotten.
Over the course of a ten year career, Gil McDougald batted .276/.356/.410 (111 OPS+, 114 wRC+), averaging 3.9 bWAR and/or 4.4 fWAR per season. The versatile McDougald played 599 games at second base, 508 at third base, and 284 at shortstop - and for this, he is often misremembered as a utility player. However, where a utility infielder tends to evoke thoughts of a 'jack of all trades, master of none' sort, McDougald was a tremendous defender at all three positions. For his career, Total Zone estimates that McDougald was worth 46 runs at second (+12 per 135 games), 13 runs at third (+4 per 135), and 16 runs at short (+8 per 135). Baseball Prospectus' FRAA and Bill James' Win Shares paint similar pictures regarding his defensive prowess, with James naming McDougald the 33rd greatest second baseman in the history of the game in his New Historical Baseball Abstract.
It is worth noting that McDougald's superb play was well-respected in his time, winning Rookie of the Year in 1951 and making six All-Star games. Casey Stengel, never one to shy away from a quote, referred to McDougald as "the best second baseman, the best third baseman and the best shortstop in the American League." Perhaps it is best to be appreciated in your own time, than to be praised when it is too late.
For further reading, I highly recommend this Gabe Costa piece, which offers a fairly comprehensive look at both the man and the numbers.