In a so-called base clogging situation, you'd either have a fast runner at first with a slow runner at second or a fast runner at second with a slow runner at third. There is a runner in scoring position in both situation. In the former, if you want to steal a base, it would have to be a double steal, so the speed of the runner at second doesn't hinder the runner at first. On a base hit, the runner on second will either stop at third or try to score. If he stops at third, the ball likely would not have gotten far enough for the runner on first to try for third if there was no runner in front of him. If he tries to score, the fast runner can advance as far as possible. In fact, he may be able to take third base on a throw home. Either way, there's no situation in which having a fast runner on first is better than having two men on with one in scoring position. Not with the players on this team, at least. Very, very few base runners have been able to steal both 2nd and 3rd at a high enough rate to even make that a strategical option. Even then you'd be focusing on scoring just one run, whereas having two men on gives you, well, two men on. In the latter scenario, or with runners at the corners, the only way having a slow runner on third would be a disadvantage is if the fast runner can steal his way to third and score on a sacrifice fly which is too shallow to score the slow runner. But again, picking the non-base clogging situation over having two men on would statistically be the wrong decision. In certain situations it may pay off to have the fast runner in position to score on a sac fly, but over the course of a season, you'd be much better off clogging up the bases. Base clogging exists in theory when focusing on the abilities of one base runner instead of the overall situation in the game, but it has no real practical presence in baseball. Managers can refer to certain situations as base clogging all they want, but as long as having that base runner in front of the fast runner is better than having the basepaths clear for the fast runner, it's not actually base clogging. As for the not having an effective base-stealing leadoff hitter comment, Piniella stated that he'd never want a catcher batting 9th to clog the bases, which means he wouldn't want a slow runner in front of the leadoff hitter. That implies to me that he's more concerned about hindering the speed of a leadoff hitter and not having back-to-back fast base runners batting in the 9th and 1st spots in the lineup.