Assuming implementation adds indirection to page images in WT cache. 
[Vamsi] : A layer between B-tree & Block manager, to resolving address cookie to a block, reading the block to memory if required, managing the relationship between the in-memory block (disk image) and in memory page,  Influencing the eviction strategies based on the ref count to in-memory block (only if the in-memory block could be evicted, may be in-memory page can be evicted)
     Design : 6
     Implementation : 14
     Test : 6