Here is one way to do it. I have changed the block size and deviation, and added my own data, in order to get some output: 
use strict;
use warnings;

my @data;
while (<DATA>) {
    my @fields = split;
    push(@data, \@fields );
}

my $block_size = 4;
my $deviation = 0.5;

my $last = $data[0];
my @candidates = ( $last );

for my $i ( 1 .. $#data ) {
    my $current = $data[$i];
    if ( within_range( $last->[3], $current->[3] ) ) {
        push( @candidates, $current );
    }
    elsif ( @candidates >= $block_size ) {
        print_block( \@candidates );
        @candidates = ( $current );
    }
    else {
        @candidates = ( $current );
    }
    $last = $current;
}
# deal with stragglers
if ( @candidates >= $block_size ) {
    print_block( \@candidates );
}

sub within_range {
    my ( $x, $y ) = @_;
    return ( abs( $x - $y ) > $deviation ? 0 : 1 );
}

sub print_block {
    my ( $lines ) = @_;
    print "BLOCK\n";
    for my $line ( @$lines ) {
        print join(' ', @$line ), "\n";
    }
}

__DATA__
1 10492 rs55998931 0.272727272727273 0.4375
1 13418 . 0.25 0.0625
1 13752 . 0.153846153846154 0.25
1 13813 . 0.0357142857142857 0.2
1 13838 . 0.0357142857142857 0.2
1 14907 rs79585140 0.5 0.555555555555556
1 14930 rs75454623 0.535714285714286 0.611111111111111
1 14933 rs199856693 0.0357142857142857 0.0555555555555556
1 14948 rs201855936 0.107142857142857 0
1 10492 rs55998931 1 0.4375
1 10492 rs55998931 1.5 0.4375
1 10492 rs55998931 1.9 0.4375
1 10492 rs55998931 2 0.4375
1 10492 rs55998931 2.6 0.4375

[download]
Output: 
BLOCK
1 10492 rs55998931 0.272727272727273 0.4375
1 13418 . 0.25 0.0625
1 13752 . 0.153846153846154 0.25
1 13813 . 0.0357142857142857 0.2
1 13838 . 0.0357142857142857 0.2
1 14907 rs79585140 0.5 0.555555555555556
1 14930 rs75454623 0.535714285714286 0.611111111111111
BLOCK
1 10492 rs55998931 1 0.4375
1 10492 rs55998931 1.5 0.4375
1 10492 rs55998931 1.9 0.4375
1 10492 rs55998931 2 0.4375

[download]
Update: see Myrddin Wyllt's explanation below as to why this won't give the desired results.

In reply to Re: extract values from a field that are consecutive and within one standard deviation of each other by tangent
in thread extract values from a field that are consecutive and within one standard deviation of each other by mulder4786

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