The problem with finding "another Bowen" isn't finding someone who can do any particular thing as well as he did. It's about finding someone who can do ALL of those things at the level Bruce did.
Physical Ability: Bruce had the height, length, and footspeed to actually inhibit players at three different positions. The only thing he didn't have physically was weight, which is why some of the only guys he struggled with were the big, physical two's and three's (think Bonzi Wells).
Fundamentals: Bruce played fundamentally sound defense. Positioning, angles, not going for blocks or steals except how the situation dictates. This is why someone like Chris Paul, who gets a ton of steals, or Marcus Camby, who gets a lot of blocks, will never be truly elite defenders... because they get these stats by taking risks rather than playing fundamentally sound basketball.
Basketball IQ: Bowen had the mental makeup and intelligence to enhance his physical gifts and fundamentals. He would get inside other players' heads, finding something that irritated them and doing it over and over (Dennis Rodman was a master at this). He would study specific players for tendencies, and take them out of their comfort zones, by making them take the shots they are least accustomed to (Battier tries to do this, too). He would apply every trick, legal and illegal, that he could use to gain an edge over another player (kind of like Manu does on the offensive end).
Mental For ude: Unlike Ron Artest, Bowen had the mental makeup where other players couldn't get in HIS head. Also, if he failed to shut someone down or they scored on a particular possession, it wouldn't change his level of effort. Bowen would come at you 100%, all the time, never getting frustrated or letting up. He was relentless. Plus, few players would be happy being known only for their defense.
The Spurs System: All of those factors would have made Bowen a great defender on any team. But he was better on the Spurs, because we have a system that allowed Bowen to devote more of his energy to defense than almost any other system in the league would have. Our offense still utilized and needed Bowen's greatest strength offensively: three point shooting, particularly from the corner. But the role we needed him for on offense required little energy relative to most starting-player-playing-time roles on most teams.
Finding any one of those things is easy. Finding two or three is hard. Finding all of them together, is almost impossible.