Many authors, (most notably Reinfeld); have criticized Morphy's Generation as, "Too weak."
This is nonsense. (In 1000 years, when humans have computer chips embedded in their brains, perhaps someone will look at Garry Kasparov's opposition and claim his opponents were too weak!! Silly.)
Professor Arpad Elo stated that you can only judge a player by the standards of his generation!! (See section 5.13 on page 81 of Dr. Elo's book, "The Ratings of Chess-Players, Past & Present.")
Quite simply, using scientific, statistical & mathematical comparisons, Morphy was easily the best player who ever lived. Just measure, "The Gap," or the distance that a player is ahead of his generation. Using this standard, Morphy was #1, Fischer was #2, and Kasparov is #3. (No others need apply!!!) (I am not the only one who thinks this. One fellow, who was nominated for for a top prize in mathematics, (The Field's Medal?); in the 1980's wrote an article concerning this subject. He too thinks Morphy was the greatest player of all time.
Ratings are not a totally reliable method either. Generally there has been a significant inflation in ELO ratings in the last 20 years. Most mathematicians agree it is in the neighborhood of [at least] one to two percent, (per year). If one adds this number to Bobby Fischer's best rating (2815 following his match with Petrosian), then Fischer's peak rating, after adjusting for inflation, would be 2860!! This compares very favorably to Kasparov.
Another thing to consider is that when Bobby was 2700-plus, there was no one within 100 rating points of Bobby! (circa 1972.) [Kasparov usually has had at least five to ten players within 100 points of his rating.]
Morphy can be and generally is considered the first modern player. If his games do not look modern, it is because he did not need the sort of slow positional systems that modern grandmasters use, or that Staunton, Paulsen, and later Steinitz developed. His opponents had not yet mastered the open game, so he played it against them and he preferred open positions because they brought quick success. He played open games almost to perfection, but he also could handle any sort of position, having a complete grasp of chess that was years ahead of his time. Morphy was a player who intuitively knew what was best, and in this regard he was much like Capablanca. He was, like Capablanca, a child prodigy; he played fast and he was hard to beat. Löwenthal and Anderssen both later remarked that he was indeed hard to beat since he knew how to defend and would draw or even win games despite getting into bad positions. At the same time, he was deadly when given a promising position. Anderssen especially complained of this, saying that after one bad move against Morphy one may as well resign. Morphy would win his won games, but if he made an error, it was still a long, hard process trying to beat him, and more likely than not the game would still go to him in the end. "I win my games in seventy moves but Mr. Morphy wins his in twenty, but that is only natural..." Anderssen moaned, explaining his poor results against Morphy. Anderssen was perhaps grateful that he did get a 70 move win, as he did not get many wins of any kind against Morphy.
Of Morphy's 59 "serious" games — those played in matches and the 1857 New York tournament — he won 42, drew 9, and lost 8.