Ivan, you were given a perfectly rational reason for the loss and it's right there in the box score. You went +3 and flat out got out-rebounded. By playing him +3 with what is essentially a 4 guard lineup, he was able to control the middle. simmie had better shooters all around than you and a big rebounding advantage (nearly 20 points subtracting the walkons). In general, I'd say you were lucky it was a sim or you might have lost one of those other games on an 3-4-5 inside matchup. I mean, come on, you only had one starter on the floor with any rebounding and he's only a 62. I'm frankly surprised you get more than 20 boards per game with that team. Petway actually had 5 rebounds, with 2 rebounding playing PF, he must have had the ball fall in his hands.
I also noticed that in your second game you fouled 3 of his guys out, that's great, but with that +3 and his big inside advantage, your guards were fouling like crazy to get back to the scorers and instead you had 3 guys foul out. That will make a big differance.
I wouldn't put too much into those national rankings either. They are pretty much meaningless unless you are playing in a full conference. When you play nearly 2/3 of your schedule vs. sims and new coachs, you are going to get some pretty gaudy stats with even an average team. With SOS of 161, your team was playing alot of patsies and lost to all the top 100 teams you played (which is what probably brought your SOS below 200 and rpi below 100 ironicly enough).
A final note to consider, PR-C actually had more improvement throughout the season than Rollins with their starting SF improving 65 pts. You played them early and those improvements meant you weren't playing the same team a month later. You take away both your walkons and PR-C is actually 6 OVR better than Rollins (which was close to the improvement differential). That being said, you did well with a 0, which is how you should play a sim generally, +3 actually played to his strengths.
Like you said, you have a decent team for a C+ prestige, but you have to realize that in itself tells you that it is pretty average and upsets will occur. If you don't like my analysis, I'm afraid I can't play you, I'm not in Smith sadly.