Is Spirit Visage giving too much MR based on it's components?

I believe the comparison between Spirit Visage and most other defensive items is a little...off. Take Adaptive Helm and Spirit Visage for example. They both cost the same total gold at 2800g. They both build from a Spectre's Cowl (25 MR). They both end up having the same amount of MR at 55 total. HOWEVER, Adaptive Helm also builds a Null-magic Mantle (an additional 25 MR) and a Rejuvenation Bead, while Spirit only has a Kindle Gem.

So why is it that the components for Adaptive Helm total 50 MR, and when combined it only gains 5 more. But the components for Spirit Visage only grant 25 total MR, and when combined it gains 30 MR more out of nowhere?

To me, this seems like quite the jump in stats without really building anymore MR other than just finishing the item. Taking other items into consideration now.

Deadman's Plate (2900g) components total Armor: 40. When combined: 60. Sunfire Cape (2900g) components total Armor: 40. When combined: 60. Abyssal Mask (2900g) components total MR: 40. When combined: 55.

What I'm trying to show with those examples is that the components' resistance stats are at least kind of close to the finished product. Where as Spirit Visage literally more than doubles without buying another piece of MR. Was this something that was merely overlooked when reworking tank items? I'm not sure, but it is extremely off in comparison to almost all other items.