Even Marshall I'm not big on personally, think even if Campbell and Hayes aren't round 1 candidates there's a very good chance they blood Max Heath, had a pretty good year in the twos.
Having a look at Ross Lyon and rucks:
2007 - Rix played 17, Clarke played 10 and Brooks played 2. Suggests a 2nd ruck was rarely used.
2008 - King played 22 games, Gardiner played 9 and Rix 1. 2nd ruck in half the games.
2009 - King played 19, McEvoy played 11 and Gardiner played 20. 2nd ruck prevalent.
2010 - King played 6, McEvoy played 10, Stanley played 7 and Gardiner 22. 2nd ruck prevalent.
2011 - McEvoy played 22, Stanley 2 and Gardiner 1. No 2nd ruck basically.
2012 - Sandi played 14, Clarke 15 and Griffin 13. 2nd ruck prevalent.
2013 - Sandi played 10, Clarke played 17, Griffin 7, Moller 1 and Hannath 12. 2nd ruck prevalent.
2014 - Sandi played 23 and Clarke played 21 with other rucks playing 6 games. 2nd ruck prevalent.
2015 - Sandi played 23, Clarke 14 and Griffin 8. 2nd ruck prevalent.
2016 - Sandi played 5, Clarke 13, Griffin 13 and others played 7. 2nd ruck very common.
2017 - Sandi played 10, Darcy 8 and Griffin 7. Almost no 2nd ruck
2018 - Sandi played 11, Jones 5, Darcy 7 and others 5. Basically no 2nd ruck again.
2019 - Sandi played 6, Jones 1, Darcy 11 and Lobb 15. Lobb was a 2nd ruck but not a genuine ruck, so basically no 2nd ruck.
So basically he either seems to go with 2 rucks or 1 ruck on a season by season basis, I'd hazard to guess that if Gardiner had been fit he'd have always played with Saints. Interestingly it was the final 3 years when he had a young Darcy (who was AFL ready) and Sandi where he actually went two rucks the least, to be fair neither of them can play forward like Gardiner could. Also of interest was how much he played Clarke (who was a very good player when fit) and Griffin (also very solid) alongside Sandi.
Ultimately my takeaway is the first ruck doesn't seem to dictate whether he plays two rucks, Sandi and King were both great one out rucks but were also when he most played a 2nd ruck, basically if he thinks one of the 2nd rucks is best 22 then he plays them and if he doesn't, then he doesn't. It also seems to really help if that 2nd ruck can play well as a forward which seemed to limit Darcy's chances a lot.
Looking at the Saints you've got Campbell, who is a 32 year old journeyman backup ruck who doesn't offer much as a forward. I'd say if he's playing then Marshall is probably the 2nd ruck and he's worthless if that's the case anyway. Hayes is a perfect 2nd ruck, not big enough to lead the ruck but showed to be a very useful forward in his few games and dangerous at the contest. He's the ideal partner.
Heath is probably the biggest question, soon to be 21 year old genuine ruck who is pretty physical from what I understand. Probably could use another year of development but there's a case for doing that at AFL level, especially as they need to cover forwards and Marshall is a legitimately good forward.
At the end of it, I still think Marshall is a must watch this preseason, ideally all the rucks are fit come round 1 so we can get an actual indicator of his spot in the side. For mine he's the single best prospect of going 120+ this year if everything falls right but he's also got so many question marks that 95 or less is just as likely.
Ahhhh rucks!
