People need to understand the difference between "tagging" and "running with", mainly because in SC terms, there is a huge world of difference!
Robbo wasn't tagging Priddis, he running with him, hence Robbo collected quite a few possessions for the amount of time he spent on the field, and was on track to be one of Brisbanes highest scorers in the game.
Tagging is a completely negative role. You sacrifice your own game, and even position in a contest, to stop the tagged player getting to the ball. You've all seen Crowley do it. For 90% of the time he had no interest in getting the ball himself, he was just interested in his opponent not getting it. Standing between him, and where he wants to be. Bumping him, scragging him, retarding him at every opportunity. He has only one goal. My opponent will not get the ball!
Run With is a completely competitive role. The Run With player has the attitude "you and me buddy, let's see who gets the ball this time!" 90% of the time he won't play himself out of position at a contest, just to stop his opponent getting the ball, he will strive for the best position possible, to get the ball himself. If and when the opportunity presents itself, he will run off that player and be creative, where as a hard tag is far less likely to do that. The Run With players first goal is "I want to win the ball in this contest, his second goal is "if I can't win it, I'm really going to give my opponent a hard time, and put him under pressure if he does get it". The Run With player can be negating, and sacrifice his own game, some of the time , the Tagger does it all of the time.
Being a run with player might, depending on the opponent and circumstances, restrict his SC score by 5 to 15 points/game. Being a tagger means you rarely score above 60 or 70.
I wouldn't be trading Robbo, if you are scared Run With roles will make his SC drop too much. He was on track to score something in the 90's and be Brisbane's leading possession getter, in what was probably not his best game, when he injured his calf. He had 23 possessions in 66% TOG, and at the end of the game, Bell was Brisbane's leading possession gatherer with 24. Taggers are never, EVER, leading possession getters, or anywhere near it. Further proof he wasn't tagging Priddis, but running with him.
I would, however, be considering trading Robbo, if Rockliff's claim earlier in the week, that Beams might be back in Round 4 or 5 is believed to be true. That will have a far greater affect on Robbo's SC than a run with role will.