Against the height of San Antonio, Dallas, and even Golden State and Phoenix (which doesn't have much height but played against Utah as if they did), Sloan has not been adept at "matching players who compl[e]ment each other" in the starting lineup. Or given that you wrote "compliment", maybe you were reporting that Millsap and Jefferson exchange pleasantries on a regular basis.
Not saying that they shouldn't start; just saying that they shouldn't play so much time together against teams that pwn them heightwise and/or on the boards. While players can ALWAYS do better and are rarely free from blame, this is a lineup and matchup problem that has been repeated several times this season; the second unit (and, sometimes, a reenergized and/or slightly realigned first unit) has sometimes been able to salvage the W later in the game, but when they haven't, it has ended in a loss.
There's no reason to dig these holes so frequently in the first quarter, and there's no reason that the coaches should let it happen. It's not just being ready to go; it's the matchups. And if the players are dogging it OR getting pwned, they should sit down for a few plays. Or longer.