If it is because in the case of a rook promotion the king can go to e7 and that would be a weaker move than capturing for the rook hangs, then I'd be surprised to learn engines actually implement that in their evaluation.
Otherwise it is because engines are stupid.
It doesn't prefer the rook, it's the same eval.
This is actually a good demonstration for kids who think the numbers are exact. Engine evaluations fluctuate depending both on the depth and the way it prunes. You'll notice it's the same line for maybe 5 moves, then it diverges. Chess isn't such a simple game that there's 1 best move every time, so this makes sense.
In other words you can analyze the same position, with the same hardware and software (same machine) for the same depth and time, and get a slightly different eval. Whenever you happened to check, the rook promotion happened to be preferred by some centipawns.
It doesn't prefer the rook, it's the same eval.
This is actually a good demonstration for kids who think the numbers are exact. Engine evaluations fluctuate depending both on the depth and the way it prunes.
In other words you can analyze the same position, with the same hardware and software (same machine) for the same depth and time, and get a slightly different eval.
Thanks for the explanation. Im still surprised then that it seems to affect the accuracy. The analysis called the queen promotion just a 'good' move and the rook promotion the best instead of calling it an alternative or at least excellent.
The analysis tool is a gimmick they can leverage to get more memberships, it's not a serious chess analysis.
It gets things roughly correct, so it's not terrible for beginners.
Can anybody explain to me, why the computer gives a better evaluation for promoting to a rook than for promoting to queen on move 10? In both cases black has basically no choice but to take making it the same situation. Would love to hear your opinions!
It won't be the promote to Q or R that is giving you the difference. It will be that further down the string of analysis the two lines differ. That will be where you get a minute difference in analysis.
Can anybody explain to me, why the computer gives a better evaluation for promoting to a rook than for promoting to queen on move 10? In both cases black has basically no choice but to take making it the same situation. Would love to hear your opinions!
On my end it's +5.13 for queen promotion, +5.09 for rook promotion and +4.59 for bishop promotion.
I feel, however, that promoting to a rook or a bishop is definitely nicer. Just as Wildekaart noted, Black is not forced to capture the promoted piece in either situation.
I had one game in the past where my opponent who played as Black promoted to a bishop on a1. Of course my opponent knew that I would capture the piece immediately after the promotion since I had a rook along the a-file. However, I wondered what would have happened if I accidentally dropped the rook on a2 instead.
With the promotion being a queen instead, it would have been a check to my king along the first rank and the system would not have allowed me to play an illegal move even if it is unintended (such as 1...a1=Q+ 2. Ra2 in this case). However, 2. Ra2 would be legal after 1...a1=B since the promoted bishop did not give a check to my king, and so the promoted bishop would have a chance to escape.
Can anybody explain to me, why the computer gives a better evaluation for promoting to a rook than for promoting to queen on move 10? In both cases black has basically no choice but to take making it the same situation. Would love to hear your opinions!