Lopez will have his good games and he will have his bad. Personally, my issue with Lopez has never been that I think he is a bad player, but rather, I think that his presence on the court forces several other players to play "left-handed" so to speak.
When Lopez is on the court, his defender is in the paint because Lopez doesn't have the versatility to step out and constantly knock down the jumper and his decreased athleticism has actually made him a poor pick and roll player according to Synergy stats (and Phoenix Suns fans). With Lopez down low, that forces Aminu and Davis outside and it gives Gordon and Rivers another obstacle to get through in the paint. Compare a Lopez/Davis frontline with an Anderson/Davis frontline and you will see what I mean. Davis can knock down the jumper and Anderson is the best three-point shooting big in the league. When Gordon beats his man off the dribble, who is going to leave their man to help out?
That being said, there is room for Lopez on this team, much like there was room for Mike Karney and Heath Evans on the Saints. Brees and the Saints pushed the ball up and down the field in three or four wide sets, ran the ball well out of the singleback, etc., but Karney and Evans were instrumental in certain situations and against certain teams.
The Saints tended to go with a fullback on 25-35% of plays and I would be more than happy seeing Lopez on the floor for that amount of time (12-17 minutes). Give the Hornets a power dimension to go along with what should be one of the best spread/motion offenses in the league in 2 years. That's fine with me. What I don't want to see, and what I worry we might see, is a situation where Anderson, Smith, and Lopez all get equal minutes and the Hornets don't get to take advantage of some of their biggest strengths. Imagine the Saints in a base offense, running I-formation 50-60% percent of the time. That is, and has always been, my worry with acquiring Lopez.