Here goes: an ace pitcher sets the tone for any club, giving it the confidence that there's a good chance for a W, every five days, all season, providing consistent quality starts and "quantity" starts -- eating innings and keeping scores close (even on days he doesn't have his best stuff), giving the bullpen a breather and preserving relief arms from burn-out that comes from bad or thin rotations, resulting in too much bulk-guy/opener/high leverage overuse.
An ace can also share with his pitching staff experiences that made him successful, such as work-outs, routines, pitch grips, books on hitters, umps, etc. Because he throws many above-average shutdown innings and outings, his supporting cast has less pressure to press, on defense and offense. His own batters can relax at the plate, knowing they don't all have to hit grand slams to outscore opponents, and because he throws so many strikes, the defense stays alert and on its toes.
An ace makes any team better -- and for fans, better to watch -- and if there's no window open yet, watch out... because if he can't create a window by firing fastballs through the wall, maybe his grateful teammates will bash one open with their Old Hickory sledge hammers.