hi,
it is hard, isn't it? i think a babies' first goal is to drive mama crazy by changing everything all the time!
the thing to keep in mind is that EASY is a sequence of events. this little, watching the clock will probably cause more confusion. as you said, some days he's just not ready for a nap yet.
now, when he's crying, i think you probably missed his sleep window & he's overtired, which is why it's harder to put him to bed. if he does that reliably at a certain time everyday, i'd try and get him into bed about 15 minutes sooner to see if that helps.
when he's just playing... i'd leave him to it & see if he'll just drift off. he may surprise you. shh/pat is mostly meant to be used when they're already crying. if he happy, i'd leave him be.
HTH