The Spurs didn't go out of their way to replace those veterans, which they could have, by getting active in trades and mortgaging their future to remain as competitive as possible that year. Instead, they took a realistic view at their chances, in light of the injuries, weighed their options and considered the external factors (ie: upcoming draft pool). By not doing everything in their power to try and win that season, some people claim that it's tanking (the same people who claimed BC signing the likes Rasual Butler was semi-tanking).
I am not a pro-tanker. However, I was at one point referred to as the 'tank commander' during the 2011 offseason. The Raptors were only a year removed from losing Bosh, had a young roster (ie: Bargnani, DeRozan, Amir, Davis) had just drafted Valanciunas (who was known to be spending another season in Europe), had just hired a new coach, had no training camp and were projected to be a bubble team at best (most experts didn't consider them a playoff team), while the 2012 draft class was expected to be fairly decent. So, given all those factors, I thought it made perfect sense to give the young players lots of playing time for both individual development and team chemistry, while giving the new coach a chance to evaluate his roster (you know, assuming a GM and coach would work together, on the same page). The team would fast-track its organic growth, while simultaneously maximizing their draft position, enabling them to add 2 top rookies to an improved young team for the 2012-2013 season. The lockout season was a write-off anyway, with the championship all but conceded to the Heat. I considered that approach to be strategic long-term team building, as opposed to outright tanking. Of course, BC decided to fast-track the rebuilding into building (despite his best new building block playing in Europe) and useless players that weren't part of the team's future lead the ragtag group to a few too many victories over truly tanking teams, resulting in the Raptors adding Ross instead of Beal/Lillard (my personal top 2 targets).
Situational management might have a tanking aspect to it, but I think it's a far cry from all-out, deliberate, blatant tanking (which includes proactively gutting the roster).