It was sure strange to see Kevin Smith in street clothes during the Philly game. But it's pretty simple to understand if you ask me.
The Lions cannot run block to save their lives. That is why they
have to use Rieff as an extra tackle/TE - to get a push (he makes a great decoy too if it becomes a pass play).
Because they stink at run blocking, the Lions need the bigger backs to punch
through small cracks in the d-line and to then run over LB's and DB's coming up
for support. Leshoure and Bell are well suited for this. Kevin Smith is not.
Smith is the best blocker and receiver of the bunch but he sadly does not hit
the hole very hard, nor does he show great vision. He doesn't really run over
people, nor does he make them miss. Leshoure can make some miss and he can run
them over. Bell runs them over. They both can be as good as Smith catching
passes so its a wash there.
In this scheme, Williams is a better replacement for either Bell or Leshoure.
Smith is thus the odd man out. A good safety net, but still the odd man out.
Bottom line is while I am sad that this is happening to Smith, I am very happy to see the Lions do something unusual with their offense. Bringing in Rieff looked like it really confused the Eagles. LB and Safeties had to come up to play the run, but Rieff is also a solid pass blocker so Stafford could easily turn it into a pass play. Wow, the Lions confusing their opponents?