Being a General Manager is not an easy thing to do. You must put up with your boss's whims (the owner(s) of the franchise), you must acquire talent that will make your team better, and you must monitor and scout the most players in any sport in order to acquire a player.
While all GMs must do these things, as well as win, to succeed, only one sport has a breed of General Manager which tops all the rest.
That sport is baseball.
First off, there is the task of trying to satisfy your owner's whims and goals for the franchise. In no other sport has there been a more difficult owner to work for than former New York Yankees owner George Steinbrenner.
Not only did Steinbrenner have ridiculous standards, but he also had very strong demands. Just ask Brian Cashman, the current Yankees GM. Cashman had to deal with possibly the most insatiable man in sports, and now must deal with a slightly smaller version of George in the form of Hank Steinbrenner.
Side note: this is not meant to bash the Steinbrenners, this is just an example.
I mean, how many other sports do you see that have had such a dominant and demanding owner that the media takes time to cover "what George might be angry about today?"
Otherwise, owners in most other sports are acting purely as managers, or baby-sitters for lack of a better name, over their GMs.
Secondly, there is the acquiring of talent.
In no other sport, possibly with the exception being soccer, is more time spent scouting players from all over the world than baseball. Not only are GMs scouting players in high schools and colleges across the U.S., but they are also scouting in Japan, as well as in the Caribbean and Latin American countries for that next top talent.
GMs must have scouted enough players in the States that they can create and fill a draft board that lasts 50 rounds, compared to the much shorter NBA and NFL drafts. Not only are there the regular draft picks, but there are also some compensation rounds for teams who lost players to free agency that occur early on in the draft. A prime example of how important the draft can be throughout its entirety is Mike Piazza, who was the Dodgers' 62nd round selection, and turned out to be the best hitting catcher of all time.
Also, GMs must scout in other countries, like the Dominican Republic, Cuba, and Japan, for rising stars which they can hope to sign.
In addition to the draft and international scouting, there are also the July 31st trading deadline and the GM Winter Meetings in Florida.
Both are times that see baseball gain a huge focus from the media, as potential deals are always being rumored and discussed, and the action from the Winter Meetings is monitored heavily.
The current installment of drama surrounding the trade deadline involves ace CC Sabathia and the Cleveland Indians. The Indians GM Mark Shapiro must decide whether he will attempt to re-sign Sabathia in the off-season, or try and trade him for top level prospects. This saga around Sabathia will consistently garner media attention up to, and even a few days past, July 31st.
While baseball GMs do not have to worry about a salary cap like NHL, NBA, or NFL, they do have to fill out five levels of baseball players, from the Major League team all the way down to the Rookie League team.
Since they do not have a salary cap, baseball GMs are forced to budget their money towards player development, potential free agents, contract negotiations, and space to take on a player's salary through a trade.
GMs also keep tabs on basically every player in the Major League, as well as a good portion of the Minor Leaguers. This duty is epitomized in the "big board" each GM has in their office, with the names of every Major League player on it, as well as the names of some Minor League players.
Also, these GMs must monitor the production and development of their Minor League teams and players if they are to have a successful farm system which stems from good scouting, and can lead to a good and successful future.
All things being considered, baseball GMs have the most difficult jobs due to the pure amount of players that they must scout and work with on an everyday basis. Also, MLB draft picks usually take at least half a year, if not more, to fully develop, as contrasted to the likes of NBA draft picks where a top selection can have an immediate impact (see Chris Paul).
Truly, as much fun as it would be to be a General Manager for a Major League Baseball franchise, having to deal with so many players can in fact be difficult.