Most Important thing you need to win battles

Opinions vary about what is the most important thing you need to win battles and skirmishes in Facebook Fleet Command , Some say pack your fleet with the most expensive unit , some say that a balances statistics is the key to victory , but for me the most important thing is the freshness of the crew. Even if the enemy fleet have a slight advantage over you if your crews state is better than there crew status you have more than a fair chance of winning that battle or skirmish.
My usual strategy is update the captains statistics and update 2 stats of the crew. Do the battle and the skirmishes for that round and rest the crew from the final training point. So whenever I visit the game again my crew is always fresh.
What do you think is the most important thing in winning battles and skirmishes ? Feel free to share your thoughts in the comments section.

Dreadnought and the submarines added

Fleet command team has introduced few new ships to keep the players interested a bit longer. One of the biggest drawbacks of the Fleet command game is that after you unlocked all the ships and completes your fleet there isn't much more to do other than playing skirmishes. The player interaction is very limited compared to other games so adding this new ships is a good way to keep the players who have being playing for a while interested. Drawback is that after acquiring few Dreadnoughts that player becomes almost unbeatable. What I like to see it a bit more player interaction in the game , what do you think ?