Speed in this game

Hi,
I am beginner, and i wonder how speed is used in the game.
My team is lvl1 14stars average but when i play against a lvl3 team average 8stars, all my players look slow, very slow...
Opponent RB just burn all my player every carry... After the game i take a look to this RB and he is only 10 in speed for a 9star overall... How can he burn in speed my LBs,S who have all more than 20 in speed, stamina, defensive acceleration...
I really don't understand how my 14 stars team can loose against a 8 stars team in automatic mode...

Thanks for clues...
Your attack speed, defense speed and rhythm in your strategy make a big difference in speed. However if you set the attack / defense speed too high your players will be inaccurate (fumble, mise tackles etc) and if your rhythm is too high it will influence your player energy levels during the game so you will need to find the correct balance.
Magic blue Q button says speed sliders hurt stamina and rhythm hurts precision, but essentially yes.

Edit: Oops, I was wrong, Q had it right.

Jeff, you've also got to consider the possibility that it was a different RB, or look at the plays you're calling. Weaker players can beat stronger ones if the defense is poor or the offense is calling better plays, and sometimes the stats are higher than the star rating. One of my best RBs is only rated at 20, but has 60 (my current stat cap) in most of the stats a RB needs.
Random extra thought:
Don't forget to factor in any difference you might have in morale and energy level.
It may not be that he has more speed, but better juke and penetration strength. Also if your defense has low anti juke and tackling then this also could be the issue. Just keep training and it will come to you. I'd say early on run no higher than 55-60% rhythm and 25% attack speed. But this is not always the case. Goodluck and have fun Jeff.
Oh and strategy building is a key thing to continue to improve .
Eh. I kept spending my money on the RP and training buildings, I only do strat when it's relatively cheap.

At champ level 3, one level of strat building is +0.25 to any maxed out stat (.5% of 50), so you'd need 3-4 levels to make any real difference.
Thanks all for your advices. My defense was "good" as antijuke 25 tackle 25 strenght 25 to all my defensive players (i reapeat i was lvl1 team, i just have been promoted to lvl3)
I have 50% rythm and 0 attack defense speed... maybe i should try to move up this sliders. But last time i put them to 10%, it was fumble fest (Rb have 20 on carry).
I precise that my players are always full rested when i'm playing games... I also increase Stamina on my players...

Thank you again for your answers.
Just an FYI regarding strength stat, that doesn't have any influence on speed, blocking or breaking tackles. Strength is actually the probability that you will injure your opponent and to counter that you upgrade toughness.
Exactly what Q said. Several of the stats are misnamed, you'll want to click the little blue ? button in the menus to get a better sense of what they really are.