None of the following is aimed at discrediting Marciano, you can't knock an unbeaten record right! He may be the greatest ever, he may be an average champion, but we will never know because his opposition was so shockingly bad!

I reckon there are probably 15-20 Heavyweights who would also have gone 49-0 against Marciano's opposition

Best wins (imo)

Moore - A 40 year old Light Heavyweight who had fought about 180 times
Charles -An over the hill Light Heavyweight veterran of around 100 fights
Walcott - A 38 year old with around 70 fights, who had lost 17 fights already and was well ahead after 12 rounds agains the Rock.
La Starza (plenty of people think he lost their first fight)
Rex Layne - always failed at the highest level
Harry Matthews - amassed a decent record, but beat nobody of note and lost whenever he stepped up.
Lee Savold 89-37-3 - decent fighter
Joe Louis - no comment needed on Louis' condition

He has the worst record of opponents (in terms of their win/loss ratios) of any Heavyweight champion in history and imo definitely operated in the wekaest division ever (even including today's division.

As I said above, he may be the greatest ever, but his resume certainly is not!!