It's not unprecedented for a team to spring up out of nowhere and become title favorites. Next year's favorites, the Miami Heat, emerged in that exact manner. The league is moving toward hastily conjured "big threes" and "big fours" if it wasn't already there in the first place.
The Lakers have some issues that hold them back from title contention, issues that Dwight Howard could help resolve were he to come West. Their defense was middling, tied for 14th in the league last year. While Andrew Bynum is a plus defender, he cannot cover up for the other holes in a plodding Lakers D. Also, Bynum is a plodder himself, leaving the Lakers vulnerable to a transition attack.
The hope would be that Howard could cover up for the defensive lapses that an aging Los Angeles frontcourt will cede while also moving quickly enough to protect L.A. from a Nuggets-like fastbreak attack. On offense, Howard could conceivably form a devastating pick-and-roll combination with P-n-R ace Steve Nash.
Dwight should improve the Lakers on defense and on offense. It remains to be seen if such improvements make the Lakers favorites.