I don't know why but for me -I'm a fast bowler- it is the opposite as I am encouraged by batsmen blocking deliveries, and am worried about batsmen who try to go for big hits. It is because I view it differently in that if the batsman blocked the ball it is either because he was in two minds, i.e: hesitant OR or he wanted to slog it and it was too good.
That's a bit wrong-headed. When you move up the ranks, you'll find that better batsmen will be able to belt even your good deliveries. If they're blocking you, generally it doesn't mean you're on top but that they're just watching you and as soon as you stray in line or length even slightly, they'll pumel you. Take it from someone who has been on the wrong end of good batsmen in form plenty of times.
I used to take encouragement from batsmen looking to hit me because it's a higher risk for them to take. If I bowled straight up-and-down and batsmen were just blocking me, I might make my figures look good but they'd also be getting themselves in and when they did, it wouldn't matter where you bowled to them because they'd be IN and going at that point. So if they were looking to go after me early in their innings, I took it as a sign of nerves because the good players don't generally do that unless they're in some real form. And even then, if they're going for it, I still had a good chance of getting them.
It's a tough thing to guage. When playing against not-so-good batsmen, them blocking me WAS a sign of encouragement, especially if they weren't doing it very well. Against good players, if they were blocking me early on, they were just taking their time to get their eye in and I always thought this was a bad sign and that I'd have to try something different to force them to play a shot or two to give myself a chance of getting them out as bowling a tight line-and-length wasn't going to cut it.
The worst sign as a pace bowler is when a batsman starts leaving you outside off-stump when the deliveries aren't that wide. It shows they know eactly where their stumps are and are either in form or are at least comfortable facing you by that point. That would mean some hard work, believe me.
I played against Mike Klinger when I played against Vic U/19's and he started off very sowly against us hitting 40 off around 130 balls as he got his eye in (bear in mind even though he batted slowly, he didn't look in any difficulty). Next thing you know he hits another 140 off his next 80 balls as he took us apart because he'd used those deliveries where we were just trying to contain him to get his eye in.
Needless to say I was a happy man when I got him fending away a short one first-ball in the second-innings and I learnt a valuable lesson that day; sure we kept him quiet initially with tight bowling but we also didn't try to force him out of his comfort-zone by encouraging him to play a few shots. As I said, once he got his eye in, it didn't matter where we bowled to him.............