From what I understand, local ($_); is roughly equivalent to:

my $saved = $_;
$_ = undef;
...
$_ = $saved;
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No, its actually equivalent to

my $tmp;
my $old = \$_;
*_ = \$tmp;
...
*_ = \$old;
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as can be seen from the following:

$ perl -le '$x = 1; $r = \$x; local $x=2; print "$$r $x"'
1 2
$
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In your example they both would have printed 2.

Dave.