Dugout Hero's rather subpar graphics and overall appearance make expectations low going in, but dont let looks fool you.
The game is only online. There is an offline option, but is just single game and the A.I. is glitched. This game is clearly centered for online, and for good reason. The game starts off with you picking a team with 2009 opening day rosters. After picking the team you have your base roster. From there you can play games against other players your level and begin to earn money. The money is this game is called, "nuts". It will take you about 2 weeks to get used to calling money nuts, and you will snicker after each game for a while seeing that you earned or lost nuts.
You can go up levels, and earn experience, but these do nothing, and are just badges of honor. Your concern is nuts (HA!). Nuts can be used to buy different "player cards". You can buy Level 1, 2, and 3 player cards as well as prospect cards. Level 1 will get a terrible player that may not even be worthy of a roster spot. Level 2 cards will get you a player that may be usable as a bench player. A level 3 is a very expensive card, but it will get you a player that you may be able to insert into your starting lineup right away.
Players on your team will play for 8 seasons. A season is 50 online games, so it takes a lot of time to finish 8 seasons. If you buy a card for a player that you don't think is ready to play, if you do not use the player for a season it does not count against them, so their 8 season cap doesn't start until their first game. By your 7th-8th season your team will look nothing like the team you started with when you first got the game.
Players' level up like your team does, but unlike your team this matters. Players will level up in Batting, Power, Speed, Fielding, and Arm. Most of your players start at a very low level, so the field is basically easy to start. (So starting with the Yankees isn't a huge advantage over starting with the Pirates.
This game has so much to offer and so much customization it is truly worth your time. It's a free game and a free download. You may get frustrated at first but as you play you will become addicted and enjoy the customization factor to make your team truly your own. Give this game a shot, you won't regret it.